PRIME, HCF & LCM REVIEW

What is the least common multiple (LCM) of 3 and 20?

• 60

• 40

• 20

• 3

Find the highest common factor of 36 and 84.

• 5

• 6

• 4

• 12

Choose the correct list of the first five multiples of 10.

• 1, 10, 20, 30, 40

• 10, 20, 30, 40, 50

• 5, 10, 15, 20, 25

• 10, 30, 40, 50, 60

All of these are prime except

• 3

• 9

• 2

• 13

Which of these is NOT a factor of 36?

• 2

• 6

• 8

• 12

Find the HCF for 18, 36, and 81

• 3

• 2

• 6

• 9

Find the LCM for 6, 18, and 36

• 6

• 18

• 36

• 108

Which shows the prime factorization of 84?

• $2\times2\times3\times7$

• $2\times2\times3\times3\times7$

• $4\times21$

• $7\times21$

Four bells ring at intervals of 6, 7, 8 and 9 seconds respectively. After how many seconds do all the bells ring together?

• 504

• 508

• 512

• 516

Three bells toll together at intervals of 9, 12 and 15 minutes. If they start toiling together, after what time will they toll next?

• $1\ hour$

• $1\frac{1}{2}hour$ 1

• $2\frac{1}{2}hour$

• $3\ hour$