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 ABILITY
Maths Questions for Competitive Examinations/ GK Maths.
Choose the correct answer from the options given below:

1. Find the sum of first 18 terms of the AP 10, 15, 20, 25………
   A. 745
   B. 845
   C. 945
2. Find the odd one out:
   A. Rectangle
   B. Triangle
   C. Pentagon
3. 5000 rupees is invested at the rate of 12 rupees p.a. for 2 years. Find simple interest?
   A. 1000
   B. 1100
   C. 1200
4. Find the distance between -3 and +3 on a number line?
   A. 3
   B. 6
   C. 4
5. Find the sum of the reciprocals of all factors of 10?
   A. 1.8
   B. 18
   C. 0.18
6. Write the next number: 6, 10, 16, 26, 42, ——–
   A. 46
   B. 54
   C. 68
7. Find the value of 32.91 + 30.09 + 0.50 + 5?
   A. 68.50
   B. 64.50
   C. 62.55
8. Find the value of 11 x 3 – 22 + 11 – 2 x 11?
   A. 0
   B. 11
   C. 22
9. Find the odd one out:
   A. 351
   B. 405
   C. 542
10. Find the sum of first 20 natural numbers?
    A. 200
    B. 210
    C. 220

Answers with Explanation:

1. 945
2. Triangle
3. 1200
4. 6
5. 1.8
6. 68
7. 68.50
8. 0
9. 542
10. 210

Explanations:

1. 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
2. Diagonals are not possible in the case of triangles. In rectangle and pentagon, we can draw diagonals.
3. Simple Interest I = PRT/100
   = 5000 x 12 x 2 /100
   = 50 x 24
   = 1200
4. 3 – (-3) = 3 + 3 = 6
5. 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. 6 + 10 = 16
   16 + 10 = 26
   26 + 16 = 42
   42 + 26 = 68
7. 68.50
8. 11 x 3 – 22 + 11 – 2 x 11 = 33 – 22 + 11 – 22 = 0
9. Other two number’s sum of the digits is 9.
10. n (n + 1)/2 = 20 (20 + 1) /2 = (20 x 21)/2 = 210.