Exercise :: Numbers - General Questions
- Numbers - Important Formulas
- Numbers - General Questions
1. | Which one of the following is not a prime number? |
|||||||
Answer: Option D Explanation: 91 is divisible by 7. So, it is not a prime number.
|
2. | (112 x 54) = ? |
||||||||||||||||||||
Answer: Option B Explanation:
|
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? |
|||||||
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 + 1] = (x3 + 1) = (x + 1)(x2 - x + 1), which is completely divisible by N, since (x + 1) is divisible by N. |
4. | What least number must be added to 1056, so that the sum is completely divisible by 23 ? |
|||||||||
Answer: Option A Explanation: 23) 1056 (45 92 --- 136 115 --- 21 --- Required number = (23 - 21) = 2. |
5. | 1397 x 1397 = ? |
|||||||||||||||||||||
Answer: Option A Explanation:
|
6. | How many of the following numbers are divisible by 132 ? |
|||||||
Answer: Option A Explanation: 132 = 4 x 3 x 11 So, if the number divisible by all the three number 4, 3 and 11, then the number is divisible by 132 also. 264 396 462 792 968 2178 5184 6336 Therefore the following numbers are divisible by 132 : 264, 396, 792 and 6336. Required number of number = 4. |
7. | (935421 x 625) = ? |
|||||||||||||||||||
Answer: Option B Explanation:
= 584638125 |
8. | The largest 4 digit number exactly divisible by 88 is: |
|||||||||
Answer: Option A Explanation: Largest 4-digit number = 9999 88) 9999 (113 88 ---- 119 88 ---- 319 264 --- 55 --- Required number = (9999 - 55) = 9944. |
9. | Which of the following is a prime number ? |
|||||||
Answer: Option D Explanation:
Clearly, 97 is a prime number.
|
10. | What is the unit digit in {(6374)1793 x (625)317 x (341491)}? |
|||||||
Answer: Option A Explanation: Unit digit in (6374)1793 = Unit digit in (4)1793 = Unit digit in [(42)896 x 4] = Unit digit in (6 x 4) = 4 Unit digit in (625)317 = Unit digit in (5)317 = 5 Unit digit in (341)491 = Unit digit in (1)491 = 1 Required digit = Unit digit in (4 x 5 x 1) = 0. |