hcf and lcm

Which of the following numbers is not a factor of 68

• 2

• 4

• 17

• 6

Answer explanation

factors of 68 are 1,2,4,17,34,68

The smallest prime number is

• 1

• 2

• 3

• 4

The smallest composite number is

• 1

• 2

• 3

• 4

1 is

• a prime number

• a composite number

• neither prime nor composite

• an even number.

The least prime number between 1 and 10 is

• 2

• 5

• 3

• 7

The greatest common factor of 8 and 20 is

• 2

• 1

• 4

• 8

Which of the following pairs of number are not co-prime?

• 7 , 15

• 12 ,49

• 18 , 23

• 12 , 21

The greatest common factor of 5, 15 and 25 is

• 1

• 5

• 10

• 15

The LCM of 6 and 18 is

• 6

• 12

• 18

• 36

Determine the smallest 3-digit number which is exactly divisible by 6, 8 and 12.

• 120

• 144

• 136

• 100

Answer explanation

lcm of 6 , 8 and 12 is 24

multiples of 24 are 24,48,72,96,120,144

smallest 3 digit number which is divisible by 6,8 and 12 is 120