# Simple Arithmetic & Mental Ability

**Simple Arithmetic and Mental ability is about model questions that you can expect for competitive examinations. Here you can find out practice problems in Maths GK.**

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

- Find the sum of first 18 terms of the AP 10, 15, 20, 25………

A. 745

B. 845

C. 945 - Find the odd one out:

A. Rectangle

B. Triangle

C. Pentagon - 5000 rupees is invested at the rate of 12 rupees p.a. for 2 years. Find simple interest?

A. 1000

B. 1100

C. 1200 - Find the distance between -3 and +3 on a number line?

A. 3

B. 6

C. 4 - Find the sum of the reciprocals of all factors of 10?

A. 1.8

B. 18

C. 0.18 - Write the next number: 6, 10, 16, 26, 42, ——–

A. 46

B. 54

C. 68 - Find the value of 32.91 + 30.09 + 0.50 + 5?

A. 68.50

B. 64.50

C. 62.55 - Find the value of 11 x 3 – 22 + 11 – 2 x 11?

A. 0

B. 11

C. 22 - Find the odd one out:

A. 351

B. 405

C. 542 - Find the sum of first 20 natural numbers?

A. 200

B. 210

C. 220

**Answers with Explanation:**

- 945
- Triangle
- 1200
- 6
- 1.8
- 68
- 68.50
- 0
- 542
- 210

**Explanations:**

- Here a = 10, d = 5, n = 18

Sum of n terms = n/2 [2a + (n – 1) d]

Sum of 18 terms = 18/2 [2 x 10 + (18 – 1) 5]

= 9[20 + 17 x 5]

= 9 x 105

= 945 - Diagonals are not possible in the case of triangles. In rectangle and pentagon, we can draw diagonals.
- Simple Interest I = PRT/100

= 5000 x 12 x 2 /100

= 50 x 24

= 1200 - 3 – (-3) = 3 + 3 = 6
- Factors of 10 are 1, 2, 5 and 10

Sum of its reciprocals = 1 + ½ + 1/5 + 1/10

= (10 + 5 + 2 + 1)/10

= 18/10

= 1.8 - 6 + 10 = 16

16 + 10 = 26

26 + 16 = 42

42 + 26 = 68 - 68.50
- 11 x 3 – 22 + 11 – 2 x 11 = 33 – 22 + 11 – 22 = 0
- Other two number’s sum of the digits is 9.
- n (n + 1)/2 = 20 (20 + 1) /2 = (20 x 21)/2 = 210.