# Simple Arithmetic & Mental Ability

**Here you can find out practice problems in Mathematics for competitive examinations. It includes Simple Arithmetic and Mental ability questions and study materials for competitive exams.**

**SIMPLE ARITHMETIC & MENTAL ABILITYMaths Questions for Competitive Examinations.Choose the correct answer from the options given below:**

- Find the product of first 5 prime numbers?

A. 720

B. 850

C. 2310 - Anu bought a watch for 700 rupees and sold it for 644 rupees. Find the loss percentage?

A. 8.5

B. 8

C. 7.5 - Find the ratio of 5 kg: 500g

A. 1: 10

B. 10:1

C. 1: 100 - If 10% of a number is 50, find 20% of that number?

A. 50

B. 500

C. 5 - LCM of 2 numbers is 96 and HCF is 4. If one number is 12, find the other number?

A. 32

B. 48

C. 12 - If the average of 25, 27, 29 and x is 28. Find the value of x?

A. 30

B. 31

C. 32 - If the sum of five consecutive numbers is 625, which is the smallest number?

A. 120

B. 123

C. 125 - If ¼ of a number is 20, find ½ of that number?

A. 20

B. 40

C. 80 - The number of prime numbers between 1 and 100 is ————–

A. 23

B. 25

C. 27 - Find the value of 3 x 12 – 5 + 6 x 0 – 1?

A. 30

B. 36

C. 41

**Answers with Explanations:**

- 2310
- 8%
- 10: 1
- 500
- 32
- 31
- 123
- 40
- 25
- 30

**Explanations:**

- First 5 prime numbers are 2, 3, 5, 7 and 11

Product = 2 x 3 x 5 x 7 x 11 = 2310 - Loss% = (loss/CP) x 100 = (56/700) x 100 = 8%
- 5 kg = 5000g

5 kg: 500 g = 5000: 500 = 50: 5 = 10: 1 - Let the number be x.

10% of x = 50

Therefore, x = 5000/10 = 500 - Product of two numbers = LCM x HCF

One number is 12 and take the other number as y, 12 x y = 96 x 4

y = (96 x 4)/12 = 32 - Average = (25 + 27 + 29 + x) / 4 = 28

(81 + x) = 28 x 4

81 + x = 112

x = 112 – 81 = 31 - Let the 5 consecutive numbers be x, x+1, x+2, x+3 and x+4

Given x + x + 1 + x + 2 + x + 3 + x + 4 = 625

5x + 10 = 625

5x = 625 – 10 = 615

x =615/5 = 123 - Let the number be x

Given ¼ of x = 20

x = 20 x 4 = 80

Now ½ of 80 = 40 - 25
- 3 x 12 – 5 + 6 x 0 – 1 = 36 – 5 + – 1 = 36- 6 = 30