Number Systems

1

If X is between -3 and -1, and Y is between -1 and 1, then X2 - Y2 is in between which of the following?

  1. -9 and 1
  2. -9 and -1
  3. 0 and 8
  4. 0 and 9
2

While writing all the numbers from 700 to 1000, how many numbers occur in which the digit at hundred's place is greater than the digit at ten's place, and the digit at ten's place is greater than the digit at unit's place?

  1. 61
  2. 64
  3. 85
  4. 91
3

A number consists of three digits of which the middle one is zero and their sum is 4. If the number formed by interchanging the first and last digits is greater than the number itself by 198, then the difference between the first and last digits is

  1. 1
  2. 2
  3. 3
  4. 4
4

The sum of two positive integers is 52 and their LCM is 168. What is the ratio between the numbers?

  1. 2 : 3
  2. 5 : 4
  3. 7 : 6
  4. 7 : 8
5

If n is a whole number greater than 1, then n2(n2 - 1) is always divisible by

  1. 12
  2. 24
  3. 48
  4. 60
6

The sum of two numbers is 10 and their product is 20. What is the sum of their reciprocals?

  1. 1
  2. 1/2
  3. 2
  4. 1/10
7

What is the last digit in 7402 + 3402?

  1. 0
  2. 2
  3. 4
  4. 8
8

The difference between the squares of two consecutive odd integers is always divisible by

  1. 16
  2. 8
  3. 7
  4. 3
9

If x is a positive even integer and y is a negative odd integer, then xy is

  1. even integer
  2. rational number
  3. odd integer
  4. none
10

A student was asked to multiply a number by 25. He instead multiplied the number by 52 and got the answer 324 more than the correct answer. The number to be multiplied was

  1. 15
  2. 32
  3. 12
  4. 25
11

What is the maximum value of m if the number 

N = 35 × 45 × 55 × 60 × 124 × 75 

is divisible by 5m?

  1. 4
  2. 5
  3. 6
  4. 7
12

If n is a natural number, then √n is

  1. always a rational number
  2. always a natural number
  3. always an irrational number
  4. either a natural number or an irrational number
13

The digit in the units place of the product 81×82×83×84×....×99 is

  1. 0
  2. 4
  3. 6
  4. 8
14

If N, N+2 and N+4 are prime numbers, then the number of possible solutions for N are

  1. 1
  2. 2
  3. 3
  4. 4
15

The sum of two numbers is 143. If the greater number is divided by the difference of the numbers, the quotient is 7. What is the difference of the two numbers?

  1. 9
  2. 11
  3. 14
  4. 15
16

The values of x which satisfy the equation 51+x + 51–x = 26 are

  1. –1, 1
  2. 0, 1
  3. 1, 2
  4. –1, 0
17

The number of prime numbers which are less than 100 is

  1. 24
  2. 25
  3. 26
  4. 27
18

What is the remainder when the number (4444)4444 is divided by 9?

  1. 4
  2. 6
  3. 7
  4. 8
19

How many times will the digit 5 come in counting from 1 to 99 excluding those which are divisible by 3?

  1. 16
  2. 15
  3. 14
  4. 13
20

What is the number of all possible positive integer values of n for which n2 + 96 is a perfect square?

  1. 2
  2. 4
  3. 5
  4. Infinite