Printable · GCSE Foundation · ages 14-16

Factors, multiples, primes, HCF and LCM worksheet — GCSE Foundation

Fifteen questions on "factors, multiples, primes, hcf and lcm" — DfE statement N4. Print it, or print three versions so neighbours cannot copy by letter; the key gives the letter for each version.

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Factors, multiples, primes, HCF and LCM worksheet — GCSE Foundation

Maths · GCSE Foundation · N4 · Factors, multiples, primes, HCF and LCM · 15 questions

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1.The number 72 can be written as 2³ × 3², and the number 108 can be written as 2² × 3³. Work out the highest common factor of 72 and 108.
(a)36
(b)6
(c)108
(d)216
2.Work out the highest common factor of 20 and 32.
(a)8
(b)4
(c)2
(d)160
3.Work out the lowest common multiple of 4 and 6.
(a)12
(b)2
(c)6
(d)24
4.Write 90 as a product of its prime factors.
(a)2 × 3² × 5
(b)2 × 45
(c)2 × 3 × 15
(d)3 × 3 × 10
5.Work out 2 × 3 × 5 + 1 and decide whether the result is a prime number.
(a)30, which is not prime
(b)31, which is not prime because 31 = 1 × 31
(c)31, which is not prime because it is a multiple of 3
(d)31, which is prime
6.Work out the highest common factor of 15 and 25.
(a)75
(b)5
(c)15
(d)3
7.At a bus station one bus leaves every 6 minutes and another leaves every 9 minutes. The two buses leave together at the start of the day. Work out how long it is until they next leave together.
(a)18 minutes
(b)54 minutes
(c)3 minutes
(d)15 minutes
8.Which statement about the number 51 is correct?
(a)51 is prime, because it is not divisible by 2, 3 or 5.
(b)51 is not prime, because it is divisible by 2.
(c)51 is prime, because it is an odd number.
(d)51 is not prime, because 51 = 3 × 17.
9.Write down a prime number between 30 and 40.
(a)33
(b)31
(c)36
(d)34
10.Write 60 as a product of its prime factors, using index notation.
(a)2 × 3 × 5
(b)2² × 3 × 5
(c)2 × 3 × 5²
(d)2² × 3² × 5
11.Tickets for a fairground ride are sold in packs of 6. Tokens for the dodgems are sold in packs of 10. Yusuf wants to buy the smallest number of packs of each so that he ends up with the same number of ride tickets as dodgem tokens. Work out how many ride tickets that is.
(a)16
(b)30
(c)60
(d)2
12.Which of these numbers is a common factor of 18 and 24?
(a)6
(b)8
(c)12
(d)9
13.Which statement about the number 91 is correct?
(a)91 is not prime, because 91 = 7 × 13.
(b)91 is prime, because it is not divisible by 2, 3 or 5.
(c)91 is not prime, because it is divisible by 3.
(d)91 is prime, because it is an odd number ending in 1.
14.Two lighthouses flash at the start of the same minute. The first lighthouse flashes every 8 minutes and the second flashes every 12 minutes. Work out how many minutes it will be until they next flash together.
(a)4
(b)24
(c)96
(d)20
15.For any two whole numbers, the product of the numbers is equal to the product of their highest common factor and their lowest common multiple. The highest common factor of 6 and 8 is 2, and 6 × 8 = 48. Work out the lowest common multiple of 6 and 8.
(a)24
(b)12
(c)48
(d)96

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