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Worksheets

Prime factors, LCM, HCF

Total questions: 35

Worksheet time: 2hrs 37mins

Name
Class
Date
1.
A prime number is...
a)
a number that has only one factor.
b)
a number that has at least two factors.
c)
a number that has more than two factors.
d)
a number that has only two factors.
(1 and itself)
2.
Joe has listed the first 4 multiples of 7 as: 
7   14    22     28
Which one is incorrect?
a)
7
b)
14
c)
22
d)
28
3.
Find the HCF of 21 and 28
a)
3
b)
4
c)
7
d)
14
4.

Which answer lists all the factors for 40?

a)

1,2,4,5,8,12,14,40

b)

1,2,3,4,5,8,10

c)

1,2,4,5,8,10,20,40

d)

1,2,4,5,6,7,8,9,10

5.

Find the LCM of 12 and 16...

a)

48

b)

36

c)

64

d)

96

6.

Which of these numbers is not prime?

a)

17

b)

25

c)

23

d)

37

7.

Name the 5th prime number.

a)

2

b)

11

c)

5

d)

7

8.

Find the HCF for 18, 36, and 81

a)

3

b)

2

c)

6

d)

9

9.

Sophie checks her bike for repairs every 9 days and Susan check hers every 12 days. If they both check their bikes today, after how many days do they next both check their bike again?

a)

HCF

b)

LCM

10.

There are two loaf cakes. One is 35cm long and one is 21cm long. They want to cut the cake up and sell the slices, but all the slices must be equal. What is the largest slices that they can cut them into?

a)

HCF

b)

LCM

11.

A carpenter got given some free wooden planks. Some are 12m long and some are 18m long. She wants to cut them up so that she has equal size planks to make using them easier. What size planks should she cut them into to avoid wasting any wood?

a)

HCF

b)

LCM

12.

Tom and Claire both like do short exercise that involve small breaks. Tom does a short burst of exercise every 2 minutes, and Claire does hers every 3 minutes. If they start doing their exercise at 9:00am, when do they both do their exercises again?

a)

HCF

b)

LCM

13.
51 is a _____________ of 3
a)
Factor 
b)
Multiple
14.
What number is a factor for EVERY number?
a)
0
b)
1
c)
2
d)
100
15.

Which shows the prime factorization of 84?

a)

2×2×3×72\times2\times3\times7

b)

2×2×3×3×72\times2\times3\times3\times7

c)

4×214\times21

d)

7×217\times21

16.

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

a)

504

b)

508

c)

512

d)

516

17.

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

a)

1 hour1\ hour

b)

112hour1\frac{1}{2}hour 1

c)

212hour2\frac{1}{2}hour

d)

3 hour3\ hour

18.

The lowest common multiple of 8,16 and p is 48. What is the possible value of p?

a)

2

b)

24

c)

32

d)

64

19.

Mary has 24 pastries and wants to share pastries with her 20 friends. The greatest number of pastries any friend can get

a)

2

b)

4

c)

5

d)

6

20.

Melanie and Martin are both building a toy train track out of connecting pieces. Melanie has pieces that are 8 cm long while Martin's pieces are 20 cm long. How long will the shortest track be that they can each build with the same length?

a)

2

b)

4

c)

20

d)

40

21.

write 140 as th product of its prime factors

a)

2x2x5x7

b)

2x2x2x2

c)

3x2x3x5

d)

7x9x5x2

22.

A number is expressed as

23 x 33 x 5.

What is the number?

a)

11

b)

72

c)

270

d)

1080

23.

How should you express 96 as a product of its prime factors?

a)

32 x 3

b)

3 x 25

c)

2 x 48

d)

1 x 25 x 3

24.

What is 720 as a product of its prime factors?

a)

24 x 32 x 5

b)

16 x 33 x 5

c)

23 x 42 x 3

d)

26 x 7

25.

Find the LCM of 120 and 150.

a)

300

b)

360

c)

450

d)

600

26.

Find the HCF of 32 and 80.

a)

8

b)

16

c)

24

d)

32

27.

What is the HCF of 72 and 120

a)

22

b)

24

c)

26

d)

28

28.

What is the LCM of 72 and 108?

a)

144

b)

216

c)

280

d)

312

29.

Ben exercises every 12 days and Isabel every 8 days. Ben and Isabel both exercised today. How many days will it be until they exercise together again?

a)

4

b)

6

c)

12

d)

24

30.
Find the HCF and LCM of 15, 20 and 35.
a)
HCF = 5 and LCM = 420
b)
HCF = 5 and LCM = 402
c)
HCF = 15 and LCM = 10500
d)
HCF = 5 and LCM = 10500
31.

Lamp A lights up every 15 minutes and lamp B lights up every 20 minutes. If at 09.00 the two lights turn on together, the second lamp will turn on together again for the second time at ...

a)

09.30

b)

09.45

c)

10.00

d)

10.30

32.
Maya had 16 red flowers and 24 yellow flowers.  She wants to make bouquets with the same number of each color flower in each bouquet.  What is the greatest number of bouquets that she can make?
a)
4
b)
2
c)
48
d)
8
33.

Derek advises a patient to have a scale every 4 months and a polish every 6 months. If they have a scale and polish today, how long will they wait before they can have both during the same appointment?

a)

HCF

b)

LCM

34.

What is a factor?

a)

a number or quantity that when multiplied with another produces a given number or expression.

b)

a number that can be divided by another number without a remainder.

c)

A Number

d)

A number experssiona to solve a multiplication problem

SHOW ANSWER

35.

HCF of 8 and 11

a)

11

b)

88

c)

8

d)

1