# Mental Arithmetic

#### Question No 1

What is average of 3, 5 and 10?

#### Select the correct answer

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

#### Question No 2

Subtract eight and nine from twenty-five.

Solution!
25 - 8 - 9 = 8.

#### Question No 4

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 5

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 6

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?

#### Select the correct answer

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 7

Divide 672 by 12.

Solution!
672 / 12 = 56.

#### Question No 8

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 9

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 10

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 11

What is average of 2 , 5 and 8?

#### Select the correct answer

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

#### Question No 12

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 13

What is 35% of 250?

#### Select the correct answer

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 14

Deduct 7.3 from 34.2.

#### Select the correct answer

Solution!
34.2 - 7.3 = 26.9.

#### Question No 15

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

#### Select the correct answer

Solution!
Select answer from options

4817673 is completely devisible by 9..

#### Question No 16

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 17

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

#### Select the correct answer

Solution!
572 is completely divisible by 6..

#### Question No 18

Add 5683 to 1729 and divide by 2.

#### Select the correct answer

Solution!
5683 + 1729 = 7412

7412 / 2 = 3706.

#### Question No 19

What is 15 multiplied by 11?

Solution!
15 * 11 = 165.

#### Select the correct answer

Solution!
25 * (200/100) = $50 Or 200 / 4 =$50.

#### Question No 54

Subtract 369 from 1250.

#### Select the correct answer

Solution!
1250 - 369 = 881.

#### Question No 55

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 56

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.

378 * ? = 252

Solution!
252 / 378 = 2/3.

#### Question No 58

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

#### Select the correct answer

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

#### Question No 59

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 60

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 61

Multiply 7 by 12 and divide by 6.

Solution!
7 * 12 = 84

84 / 6 = 14.

#### Question No 62

What is 45% of 300?

#### Select the correct answer

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

Hence, 135 is correct answer..

#### Question No 63

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 64

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 65

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 66

What is average of 12 , 15 and 18?

#### Select the correct answer

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

#### Question No 67

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

#### Select the correct answer

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

2664/12/6=?

#### Select the correct answer

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

100/101 = ?

#### Select the correct answer

Solution!
100/101 = 0.990099.

#### Question No 70

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 71

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 72

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 73

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

#### Select the correct answer

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 74

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 75

Divide 56 by 8 and add 17.

Solution!
56 / 8 = 7

7 + 17 = 24.

#### Question No 76

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 77

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 78

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

Solution!
100 - 64 = 36%.

#### Question No 79

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 80

What is 126 divided by 3?

Solution!
126 / 3 = 42.

#### Question No 81

Multiply 7 by 4 by 6.

Solution!
7 * 4 = 28

28 * 6 = 168.

#### Question No 82

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 83

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

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

#### Question No 84

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

#### Select the correct answer

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

#### Question No 85

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 86

Divide 52 by 4 and add 17 multiplied by 3.

Solution!
52 / 4 = 13

17 * 3 = 51

13 + 51 = 64.

#### Question No 87

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 88

What is 5/9 of 270?

#### Select the correct answer

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

#### Question No 89

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 90

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 91

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

Solution!
86 * 9 = 774

13 * 6 = 78

774 + 78 = 852.

#### Question No 92

7/21 in lowest term is?

Solution!
7/21 = 1/3.

#### Question No 93

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 94

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 95

Deduct 865 from 1063.

#### Select the correct answer

Solution!
1063 - 865 = 198.

#### Question No 96

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

Solution!
(2/5) * 90 = 36

(5/6) * 78 = 65

36 + 65 = 101.

#### Question No 97

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 98

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 99

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 100

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

#### Select the correct answer

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