Playing With Numbers

H.C.F of 396 (= 2² × 3² × 11) and 1080 (= 2³ × 3³ × 5) is

1. 2² × 3²
2. 2³ × 3³
3. 2 × 3 × 5 × 11
4. 2³ × 3³ × 5 × 11

Greatest and smallest 3-digit numbers which are exactly divisible by 3, 5, 15 are

1. 45 and 945
2. 75 and 980
3. 105 and 990
4. 120 and 975

144 is expressed as sum of twin primes as

1. 71 + 73
2. 72 + 72
3. 36 + 108
4. 32 + 112

Any two prime numbers are

1. Odd numbers
2. Even numbers
3. Composite numbers
4. Co-prime numbers

All the multiples of 2 are

1. Prime numbers
2. Even numbers
3. Odd numbers
4. Divisible by 4

Prime factors of 1323 are

1. 3³ × 3³
2. 3² × 7³
3. 3³ × 7²
4. 3² × 7³

H.C.F of 1017, 1050, 2511 is

1. 2
2. 3
3. 5
4. 7

The smallest number which when diminished by 3 is divisible by 12, 16, 24, 36 is

1. 147
2. 154
3. 185
4. 210

Product of two numbers is 2160 and their H.C.F is 12. The L.C.M of these numbers is

1. 1030
2. 720
3. 320
4. 180

The incorrect option is

1. Product of three consecutive numbers is always divisible by 6
2. Sum of two consecutive odd numbers is divisible by 4
3. A number divisible by 4 and 8 must be divisible by 4×8=32
4. 25110 is divisible by 45

The correct option is

1. A number divisible by both 3 and 7 is also divisible by 21
2. A number divisible by 185 is divisible by 3 and 6
3. If two numbers are co-prime, one of them must be prime
4. Numbers divisible by 6 must also be divisible by 12

1023 and 1078 are both divisible by 11. Therefore 1023 + 1078 will be divisible by

1. 3
2. 7
3. 11
4. 13

Number 10824 is divisible by

1. 11 only
2. 3 and 11 only
3. 2, 3, 4, 6, 9 and 11
4. 2, 3, 4, 6 and 11

Five consecutive composite numbers between 25 and 50 with no prime number between them are

1. 25, 26, 27, 28, 29
2. 32, 33, 34, 35, 36
3. 37, 38, 39, 40, 41
4. 48, 49, 50, 51, 52

Untrue statement about the number 2 is

1. 2 is the smallest prime number
2. Every prime number other than 2 is odd
3. Multiples of 2 are prime numbers
4. 2 is the smallest even number

The option which best suits '1 has only factor 1 itself' is

1. 1 is a factor of every number
2. Every composite number has 1 as a factor
3. 1 is a natural number
4. 1 is neither prime nor composite

The largest factor of 10576 is

1. 1322
2. 2644
3. 5288
4. 10576

The number of multiples of 50 is

1. Limitless
2. 200
3. 150
4. 100

Which of the following is the correct statement?

1. Factors are infinite
2. Multiples are finite
3. 1 is a factor of every number
4. Every number is not a multiple of itself

The option which suits the condition 'Every multiple of a number is greater than or equal to that number' is

1. Number of multiples of a given number is infinite
2. Multiples of 7 are 7, 14, 21, 28...
3. Factors of 7 are 1 and 7
4. Every number is a multiple of itself

Which statement suits the situation — Factors of 34 are 1, 2, 17, 34?

1. A number can have only four factors
2. Every factor is equal to given number
3. Every factor is less than or equal to given number
4. Every factor is greater than the given number