# Mental Arithmetic

#### Question No 1

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 2

What is 55% of 320?

#### Select the correct answer

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 3

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

#### Select the correct answer

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

#### Question No 4

What is 5/8 of 240?

#### Select the correct answer

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

#### Question No 5

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

#### Select the correct answer

Solution!
No answer description available for this question..

#### Question No 6

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

#### Select the correct answer

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 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 9

Multiply 6.85 by 7.

#### Select the correct answer

Solution!
6.85 * 7 = 47.95.

#### Question No 10

Multiply 7 by 12 and divide by 6.

Solution!
7 * 12 = 84

84 / 6 = 14.

#### Question No 11

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

#### Select the correct answer

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

#### Question No 12

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

#### Select the correct answer

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

2664/12/6=?

#### Select the correct answer

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

#### Question No 14

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.

#### Select the correct answer

Solution!

In this question weighted average is calculated rather than simple average

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

#### Question No 15

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?

#### Select the correct answer

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 16

Which of the following fractions is closed to 0.5?

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

#### Question No 17

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

#### Select the correct answer

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..

#### Question No 18

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

#### Select the correct answer

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

#### Question No 19

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

#### Select the correct answer

Solution!
572 is completely divisible by 6..

#### Question No 20

Multiply 15 by 6 and subtract 29.

Solution!
15 * 6 = 90

90 - 29 = 61.

#### Question No 21

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

#### Select the correct answer

Solution!
x/30 = 30/20

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

#### Question No 22

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

#### Select the correct answer

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 23

Which one of the following is a prime number ?

#### Select the correct answer

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

#### Question No 24

What is 3/4 of 92 plus 13?

Solution!
(3/4) * 92 = 69

69 + 13 = 82.

#### Question No 25

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

#### Select the correct answer

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 26

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

#### Select the correct answer

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

#### Question No 27

Add 5683 to 1729 and divide by 2.

#### Select the correct answer

Solution!
5683 + 1729 = 7412

7412 / 2 = 3706.

#### Question No 28

What is 8/40 expressed as a decimal?

#### Select the correct answer

Solution!
Simple way is

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

#### Question No 29

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

#### Select the correct answer

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 30

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?

#### Select the correct answer

Solution!
Shadow of 40m pole = 30m

Shadow of 1m pole = 30/40m

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

#### Question No 31

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

#### Select the correct answer

Solution!
No answer description available for this question..

#### Question No 32

Multiply 694 by 11.

#### Select the correct answer

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 33

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

#### Select the correct answer

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

#### Question No 34

Divide 56 by 8 and add 17.

Solution!
56 / 8 = 7

7 + 17 = 24.

#### Question No 35

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

#### Select the correct answer

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

42+x = 55

x = 55-42
=13.

#### Question No 36

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

#### Select the correct answer

Solution!
40/8 = 5

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

7 * 5 = 35.

#### Question No 37

Subtract 369 from 1250.

#### Select the correct answer

Solution!
1250 - 369 = 881.

#### Question No 38

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?

#### Select the correct answer

Solution!
x/15 = 10/3

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

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

#### Question No 39

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 40

Divide 672 by 12.

Solution!
672 / 12 = 56.

#### Question No 41

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?

#### Select the correct answer

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 42

What is average of 2 , 5 and 8?

#### Select the correct answer

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

100/101 = ?

#### Select the correct answer

Solution!
100/101 = 0.990099.

#### Question No 44

What is 3206 divided by 7?

#### Select the correct answer

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 45

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 46

7/21 in lowest term is?

Solution!
7/21 = 1/3.

#### Question No 47

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

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

#### Question No 48

Subtract eight and nine from twenty-five.

Solution!
25 - 8 - 9 = 8.

#### Question No 49

What is 15 multiplied by 11?

Solution!
15 * 11 = 165.

#### Question No 50

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

#### Select the correct answer

Solution!
(5/8) * 112 = 70

and
(7/8) * 88 = 77

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

#### Question No 51

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

#### Select the correct answer

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

#### Question No 52

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

#### Select the correct answer

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 53

Add 32 + 8 + 18 + 25.

Solution!
32 + 8 = 40

40 + 18 = 58

58 + 25 = 83.

#### Question No 54

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

#### Select the correct answer

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

#### Question No 55

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 56

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

Solution!
6+5+4 = 15.

#### Question No 57

What is 10 less 5/9 of 117?

Solution!
(5/9) * 117 = 65

65 - 10 = 55.

378 * ? = 252

Solution!
252 / 378 = 2/3.

#### Question No 59

Multiply 7 by 4 by 6.

Solution!
7 * 4 = 28

28 * 6 = 168.

#### Question No 60

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

#### Select the correct answer

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 61

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?

#### Select the correct answer

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 62

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

#### Select the correct answer

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 63

What is the sum of first 5 positive even integers?

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

#### 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?

#### Select the correct answer

Solution!
Thrift numbers between 0 and 15 are following

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

#### Question No 65

Which of the following is a prime number?

#### Select the correct answer

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 66

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

#### Select the correct answer

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

Or

#### Select the correct answer

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 86

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

#### Select the correct answer

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 87

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

Solution!
86 * 9 = 774

13 * 6 = 78

774 + 78 = 852.

#### Question No 88

Deduct 865 from 1063.

#### Select the correct answer

Solution!
1063 - 865 = 198.

#### Question No 89

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 90

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

#### Select the correct answer

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..

#### Question No 91

Deduct 7.3 from 34.2.

#### Select the correct answer

Solution!
34.2 - 7.3 = 26.9.

#### Question No 92

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 93

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 94

What is average of 12 , 15 and 18?

#### Select the correct answer

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

2+2*2?

#### Select the correct answer

Solution!
2 + (2 * 2) = 6

Multiplication is performed first and subtraction afterwards.

Sequence of solving operators is
/
*
+
-.

#### Question No 96

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 97

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?

#### Select the correct answer

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

#### Question No 98

What is 5/9 of 270?

#### Select the correct answer

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

#### Question No 99

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?

#### Select the correct answer

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 100

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

#### Select the correct answer

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