# Mental Arithmetic

#### Question No 1

Ali can type at a speed of 25 words per minute. How many words he can type in one hour?

Solution!
Typed words in 1 minute = 25
Typed words in 60 minutes = 60 * 25 = 1500.

#### Question No 2

If n is not equal to 0, Which of the following must be greater than n? (1) 2n (2) n^2 (3) 2-n

Solution!
Square of every non zero integer is grater than the orignal number.

*Note that multiple of 2 of negative numbers are lesser than the orignal number..

Or
200 / 4 = $50. #### Question No 4 The average of five numbers is 27.If one number is excluded the average becomes 25.What is the excluded number? #### Select the correct answer Solution! No answer description available for this question.. #### Question No 5 Which of the following is the least number which is divisible by both 12 and 18? #### Select the correct answer Solution! Least common multiple of 12 and 18 is 36. #### Question No 6 49/10 + 49/10 + 49/10 = ? #### Select the correct answer Solution! By taking LCM of these three terms we have (49+49+49)/10 = 147/10. #### Question No 7 Multiply 72 by 15. #### Select the correct answer Solution! 72 * 15 = 1080 Other way is 72 * 10 = 720 and 720 / 2 = 360 720 + 360 = 1080. #### Question No 8 If m is an even integer and 3m < 48 and 2m > 24 then m = ? #### Select the correct answer Solution! 3*14 = 42 (lesser than 48) and 2*14 = 28 (greater than 24).. #### Question No 9 Add 5683 to 1729 and divide by 2. #### Select the correct answer Solution! 5683 + 1729 = 7412 7412 / 2 = 3706. #### Question No 10 If a amount of$120 is divided among A and B in the ratio 1/2 then A will get?

Solution!
A will get half amount which B got.So if A's amount is 40, B's amount will be 80 (double of A's amount)..

#### Question No 11

At a particular time shadow of a pole 40m long is measured to be 30m. If the length of a plaza is 200m then how long would the shadow be at about the same time?

Solution!
Shadow of 40m pole = 30m

Shadow of 1m pole = 30/40m

Shadow of 200m plaza = (30/40)*200 = 150m.

#### Question No 12

7/21 in lowest term is?

Solution!
7/21 = 1/3.

#### Question No 13

What must be added to each numerator and denominator of 13/29 so that it becomes 1/2

Solution!
(13+3)/(29+3) = 1/2.

#### Question No 14

What is 10 less 5/9 of 117?

Solution!
(5/9) * 117 = 65

65 - 10 = 55.

#### Question No 15

Add 2/5 of 90 to 5/6 of 78.

Solution!
(2/5) * 90 = 36

(5/6) * 78 = 65

36 + 65 = 101.

#### Question No 16

Multiply 7 by 4 by 6.

Solution!
7 * 4 = 28

28 * 6 = 168.

#### Question No 17

The side of a square is 2. What is the area of the square?

Solution!
Area of square is
2 * (any side)
= 2 * (2) = 4 square units.

#### Question No 18

What is average of 2, 5 , 6 , 9 and 18?

Solution!
(2+5+6+9+18)/5 = 40/5 = 8.

#### Question No 19

What is average of 2 , 5 and 8?

Solution!
(2+5+8)/3 = 15/3 = 5.

#### Question No 20

What is the largest 4 digit number exactly divisible by 88?

Solution!
No answer description available for this question..

#### Question No 21

What is average of 12 , 15 and 18?

Solution!
(12+15+18)/3 = 45/3 = 15.

#### Question No 22

What is smallest integer greater than 1 that leaves remainder 1 when it is divided by 5 or 8?

Solution!
40 is the least common multiple of 5 and 8 so 41 will be the smalles integer that leaves 1 when it is divided by 5 or 8..

#### Question No 23

Multiply 15 by 6 and subtract 29.

Solution!
15 * 6 = 90

90 - 29 = 61.

#### Question No 24

Average of 4 numbers is 24. What is the sum of the four numbers?

Solution!
x/4 = 24
x = 24*4
x = 96.

#### Question No 25

What is average of 3, 5 and 10?

Solution!
(3+5+10)/3 = 18/3 = 6.

#### Question No 26

2+2*2?

Solution!
2 + (2 * 2) = 6

Multiplication is performed first and subtraction afterwards.

Sequence of solving operators is
/
*
+
-.

#### Question No 27

John can read 8 pages of a book in 7 minutes, how long will he take to read 40 pages?

Solution!
40/8 = 5

As pages are increased 5 times. So minutes will also increase 5 time.

7 * 5 = 35.

#### Question No 28

Price of a mobile phone is Rs. 8,000. A man has enough money to purchase 3 mobiles. How many mobile can he purchase if the price is reduced by Rs. 2000?

Solution!
Minimum amount of money that he has = 8,000 * 3 = 24,000

If price is reduced to 6,000, he can purchase 24,000/6,000 = 4.

#### Question No 29

15 weavers can weave some length of cloth in 1 hr. 24 minutes. How many more weavers are required to do the same job in 60 minutes?

Solution!
x/15 = 84/60

x = (84/60)*15 = 21

So 21 - 15 = 6 more weavers are required to do the same job in 60 minutes..

#### Question No 30

Multiply 86 by 9 and add to 13 multiplied by 6.

Solution!
86 * 9 = 774

13 * 6 = 78

774 + 78 = 852.

#### Question No 31

Divide 672 by 12.

Solution!
672 / 12 = 56.

#### Question No 32

What is 9 multiplied by 8?

Solution!
9 * 8 = 72.

#### Question No 33

At an educational trip of a school ratio of boys to girls students was 4/5. how many students were on the tour?

Solution!
Data is insufficient for this problem. But we can find the answer from the options. As 4 + 5 = 9, So answer should be multiple of 9 to fullfil the condition of 4/5 ratio..

#### Question No 34

64% of the children in school are girls.What percentage are boys?

Solution!
100 - 64 = 36%.

#### Question No 35

If A/B is 2/3 and difference between values of A and B is 10 What is value of B?

Solution!
If B is 30, A is 20 so difference of 10 is maintained..

#### Question No 36

What is the average of 8, 13, 25, 43, and 11?

Solution!
(8+13+25+43+11)/5 = 100/5
= 20.

#### Question No 37

If x = 8*89 and y = 8*85, What is the value of x-y ?

Solution!
(8*89) - (8*85)
=8*(89 - 85)
=8*(4)=
32.

#### Question No 38

What is 126 divided by 3?

Solution!
126 / 3 = 42.

#### Question No 39

Divide 52 by 4 and add 17 multiplied by 3.

Solution!
52 / 4 = 13

17 * 3 = 51

13 + 51 = 64.

#### Question No 40

Deduct 7.3 from 34.2.

Solution!
34.2 - 7.3 = 26.9.

#### Question No 42

John's fail to pass ratio in mathematics test is 5/2. In how many tests did he pass if total tests conducted were 42?

Solution!
Pass ratio = (2/7)*42 = 12.

#### Question No 43

What is 5/8 of 240?

Solution!
(5/8) * 240 = 150.

#### Question No 44

Multiply 7 by 12 and divide by 6.

Solution!
7 * 12 = 84

84 / 6 = 14.

#### Question No 45

In a box ratio of DVD to VCD is 2/3. Which of the following cannot be the total number of CD's in the box?

Solution!
As 2+3 = 5, So total number of CD's must be multiple of 5.

In the options all are multiple of 5 except 11

So 11 is the correct answer..

#### Question No 46

A bus covers a distance of 60 Km in 1.5 hr. How far it would travel in half hour.

Solution!
Distance covered in 1.5 hr = 60

Distance covered in 1 hr = 60/1.5 = 40 Km

Distance Covered in 0.5 hr = 40 * 0.5 = 20.

#### Question No 47

35 Kg of spinach costs Rs. 28. How many Kg of spinach can be bought for Rs. 16?

Solution!
Amount of spinach which can be bought in Rs. 28 = 35 kg

Amount of spinach which can be bought in Rs. 1 = 35/28 = 5/4 Kg

Amount of spinach which can be bought in Rs. 16 =(5/4)*16 = 20 Kg.

#### Question No 48

What is 45% of 300?

Solution!
45 * (300/100) = 135

Quick way to find answer from options is

50% of 300 is 150 so 45% of 300 should be less than 150

So, it may be 149 or 135
149 is very close to 150 which is not possible

#### Question No 49

What is 5.9 + 6.8 + 7.34?

Solution!
6.8 + 7.34 = 14.14

14.14 + 5.9 = 20.04.

#### Question No 50

Deduct 865 from 1063.

Solution!
1063 - 865 = 198.

#### Question No 51

If the number 481z673 is completely divisible by 9, what is the the smallest whole number in place of z?

Solution!

4817673 is completely devisible by 9..

#### Question No 52

In a class the ratio of boys to girls is 1/3. What percent of students are girls?

Solution!
Percentage of girls in class = (3/4)*100 = 75%.

#### Question No 53

If p is and odd integer and 7p > 50 and 3p < 35 then p is?

Solution!
7*11 = 77 (greater than 35) and 3*7 = 33 (lesser than 35)

*Note that 8 is also true but in question it is explicitly said that integer must be odd..

#### Question No 54

Multiply 694 by 11.

Solution!
694 * 11 = 7634

Quick way to find answer from options is

694 * 10 = 6940

So answer must be greater than 6940 and only one option is greater than 6940 which is 7634..

#### Question No 55

Subtract 369 from 1250.

Solution!
1250 - 369 = 881.

#### Question No 56

If average of 8, 7, 12, 15 and x is 11 what is x?

Solution!
(8+7+12+15+x)/5 = 11

42+x = 55

x = 55-42
=13.

#### Question No 57

In the first 10 overs of a cricket game the run rate was only 3.2 What should be the run rate in the remaining 40 overs to reach the target of 282?

Solution!
3.2 * 10 = 32

After 10 overs score is 32.

Remaining score = 282 - 32 = 250

Required rate = 250 / 40 = 6.25 runs/over.

#### Question No 58

What is 3206 divided by 7?

Solution!
3206 / 7 = 458

No need to perform complete devision first digit comes 4 after devision and there is only one option in which first digit is 4..

#### Question No 59

A/B = 2/3. If value of A is 8 What is the value of B?

Solution!
8/B = 2/3
2B = 24
B = 12

*In short-cut way We can find 2 is multiplied by 4 to get 8 so if we multiply 3 with 4 we get 12 which is the value b B when value of A is 8..

#### Question No 60

What is 55% of 320?

Solution!
55 * (320 / 100) = 176

Quick way to find answer from options is

50% of 320 is 160 so answer should be greater than 160
Only one option is greater than 160 which is 176..

#### Question No 61

If the number 5r2 is divisible by 6, then r = ?

Solution!
572 is completely divisible by 6..

#### Question No 62

Which of the following fractions is closed to 0.5?

Solution!
15/30 = 1/2
1/2 = 0.5.

#### Question No 63

What is 5/9 of 270?

Solution!
(5/9) * 270 = 150.

#### Question No 64

A number is thrift if it is a multiple of 2 or 3. How many thrift numbers are there between 0 and 15?

Solution!
Thrift numbers between 0 and 15 are following

2,3,4,6,8,9,10,12,14.

#### Question No 65

A cycle costs $170.Jane saves$50 each week.How many weeks will it be before she can buy it?

Solution!
170 / 50 = 3.4
But 3.4 is not in options so nearest Option is 4.

#### Question No 66

Ahmad reads 24 pages of a book in 15 minutes. The rate of pages read per minute by him will be

Solution!
24/15 = 8/5
8/5 = 1.6.

#### Question No 67

What is the difference of the product and the quotient of 8 and 8?

Solution!
8*8 = 64
and
8/8 = 1
So,
64 - 1 = 63.

#### Question No 68

If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, what is the average marks of all the students?

Solution!
Weighted average will be more close to the average of that batch which has maximum number of students so aanswer is 54.68

If you want to calculate it by formula then solution is

(55*50 + 60*55 + 45*60)/(55 + 60 + 45) = 54.68.

#### Question No 69

15 men were hired to plough a piece of land in 10 days. How many more men will be required to do the same job in 3 days?

Solution!
x/15 = 10/3

x = (10/3)*15
x = 50.

So more number of men required = 50-15 = 35.

#### Question No 70

100/101 = ?

Solution!
100/101 = 0.990099.

#### Question No 71

The average of 20 numbers is 0, How many of them may be greater than zero,at the most?

Solution!
Maximum Numbers that can be greater than 0 to maintain total average greater than 0 are 19..

#### Question No 72

Average of 3 numbers is 15. What is the sum of 3 numbers?

Solution!
Let sum is x.

x/3 = 15
x = 15*3 = 45.

#### Question No 73

If the product of 4 consecutive integers is 120, which is greater?

Solution!
5*4*3*2 = 120.

#### Question No 74

Which one of the following is a prime number ?

Solution!
307 is only number which is divisible by 1 and by itself only..

#### Question No 75

Which of the following is an integer that has a remainder of 1 when it is divided by 4,5 and 6?

Solution!
Least common multiple of 4,5 and 6 is 60 so 61 is an integer that has a remainder of 1 when it is divided by 4,5 and 6..

#### Question No 76

What is the sum of first 5 positive even integers?

Solution!
2+4+6+8+10 = 30.

#### Question No 77

In a Zoo deers and lions are in ratio of 5/2. If there are 20 deers how many lion are there?

Solution!
20 is 4 times of 5 So in this way 4 times of 2 will be 8..

#### Question No 78

Sum of three consecutive odd integers is 51. Which of the following is the smallest of the three?

Solution!
19+17+15 = 51.

#### Question No 79

Which is greater, (A) 5/8 of 112 , (B) 7/8 of 88?

Solution!
(5/8) * 112 = 70

and
(7/8) * 88 = 77

Hence, (7/8) of 88 is greater..

#### Question No 80

When R is divided by 7 remainder is 3. What is the remainder when 3R is divided by 7?

Solution!
No answer description is available for this question..

#### Question No 81

Which of the following is a prime number?

Solution!
A prime number is the number which is divisible by 1 and by itself only

and 2 is the only one even number which is prime..

#### Question No 82

If one third of the staff at school are teachers find the ratio between teachers to non-teachers.

Solution!
ratio of teachers = 1/3

ratio of non-teachers = 2/3

Ratio of teachers to non-teachers = (1/3) * (3/2) = 1/2.

#### Question No 83

Subtract eight and nine from twenty-five.

Solution!
25 - 8 - 9 = 8.

#### Question No 84

What is 8/40 expressed as a decimal?

Solution!
Simple way is

(8/4) * (1/10) = 2 * 0.1 = 0.2.

#### Question No 85

If n is even, Which of the following cannot be odd? (1) n+3 (2) 3n (3) n^2 - 1

Solution!
3n and n^2 - 1 will always odd so in case of 3n answers will be even..

#### Question No 86

Add 32 + 8 + 18 + 25.

Solution!
32 + 8 = 40

40 + 18 = 58

58 + 25 = 83.

#### Question No 87

What is 15 multiplied by 11?

Solution!
15 * 11 = 165.

#### Question No 88

A coach trip starts at nine fifty.It lasts twenty-five minutes.At what time does it finish?

Solution!
No answer description available for this question..

#### Question No 89

The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg.Find the average weights of all the boys in the class.

Solution!

In this question weighted average is calculated rather than simple average

(50.25*16 + 45.15*8)/(16+8) = 48.55.

#### Question No 90

A motorcyclist travels 200 Km in 1 hr. How many minutes if would take him to travel 120 Km?

Solution!
200 Km distance covered in minutes = 60

1 Km distance covered in minutes = 60/200 = 3/10

120 Km distance covered in minutes = (3/10) * 120 = 36 minutes.

#### Question No 91

30 men can complete a work in 30 days how long will 20 men take to complete the same amount of work?

Solution!
x/30 = 30/20

x = (30/20)*30 = 45.

#### Question No 92

16 men dig a ditch in 10 days. How many men would be required to complete the job in half the time?

Solution!
Double number of men are required to complete the job in half time..

#### Question No 93

Multiply 6.85 by 7.

Solution!
6.85 * 7 = 47.95.

#### Question No 94

2664/12/6=?

Solution!
(2664/12) * (1/6) = 37.

#### Question No 95

What is 35% of 250?

Solution!
35 * (250/100) = 87.5

Quick way to find answer from options is

33% of 250 is nearly 83(250/3 = 83.3)

So, answer should be in 80's which is only one option 87.5.

#### Question No 96

A cigarette case is full of cigars and cigarettes, probability of a cigarette is 8/15. What is the ratio of cigars to cigarettes.

Solution!
In 15 cigars and cigarettes there are 8 cigarettes So ratio between cigars and cigarettes is 8/7. Which means there are 8 cigarettes and 7 cigars..

378 * ? = 252

Solution!
252 / 378 = 2/3.

#### Question No 98

What is 3/4 of 92 plus 13?

Solution!
(3/4) * 92 = 69

69 + 13 = 82.

#### Question No 99

Divide 56 by 8 and add 17.

Solution!
56 / 8 = 7

7 + 17 = 24.

#### Question No 100

If the sum of three consecutive whole numbers is 15, what is the largest of the three numbers?

Solution!
6+5+4 = 15.
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## Tips to Solve Mental Arithmetic Test

Mental arithmetic is an awesome brain-storming math IQ test that is done without a calculator. It is to check the sharpness of mind and how quickly a student or even an interviewing candidate can solve the arithmetic problems. Most candidates and students opt for mental math classes to practice solving Math problems in the mind and not using the pen or paper. The mental arithmetic involves four types of calculations generally like addition, subtraction, division, and multiplication. Its main aim is to improve cognitive ability and help brain function faster.

This maths IQ test helps you to simplify the calculations and get the answers quickly. Like, if we have to add two numbers like 91 and 45 then use the simplified steps. Firstly, add the second numbers of both the digits like 1 + 5= 6 and then add the first numbers of these digits like 9+4 = 13 so the total answer is 136 where you need to place answers of second numbers on the second place and the answer of first numbers on the first place. This way you can solve the subtraction problems too.

While, in multiplication problems, you have to place zero at the end of two-digit numbers like 3X75, so it goes like 3x70 and 3x5 so the answer is 210+15= 225. This way you will get the exact answers. There are varied rules for square roots, divisions, etc. Here you can learn by practicing the various significant rules of the Mental arithmetic. It will help you to solve tedious questions too. 