Aptitute Questions

1.Which one of the following is not a prime number?
A. 31 B. 61
C. 71 D. 91
Answer: Option D
Explanation:
91 is divisible by 7. So, it is not a prime number.
2. (112 x 54^4) = ?
A. 67000 B. 70000
C. 76500 D. 77200
Answer: Option B

Explanation:

(112 x 54^4)= 70000
3. It is being given that (232 + 1) is completely divisible by a whole number. Which of the following numbers is completely divisible by this number?
A. (216 + 1) B. (216 - 1)
C. (7 x 223) D. (296 + 1)
Answer: Option D

Explanation:

Let 232 = x. Then, (232 + 1) = (x + 1).

Let (x + 1) be completely divisible by the natural number N. Then,

(296 + 1) = [(232)3] = (x3 + 1) = (x + 1)(x2 - x + 1), which is completely divisible by N, since (x + 1) is divisible by N.