Common factors

1 Kimisusingcounterstofindfactorsof18

Shearrangesthecountersinonerow.

Thenshearrangesthecountersintworows.

a) Kim’sarrayshowsfournumbersthatarefactorsof18

Whichnumbersarethey?

b) Whatarethetwootherfactorsof18?

c) Usecounterstofindthefactorsof27

Listthefactorsof27

d) Listthecommonfactorsof18and27

Whyarethesenumberscommonfactors?

2 Completethesentences.

a) Thefactorsof24are

Thefactorsof36are

Thecommonfactorsof24and36are

b) Thefactorsof30are

Thefactorsof45are

Thecommonfactorsof30and45are

3 a) Writethenumbersonthediagram.

1 3 5 7 21 35

b) Whatarethecommonfactorsof21and35?

c) HowdoestheVenndiagramhelpyoutolistthe

commonfactors?

©WhiteRoseMaths2019

factorsof21 factorsof35

©WhiteRoseMaths2019

4 Listthecommonfactorsofeachpairofnumbers.

a)

b)

5 Circlethepairsofnumbersthathaveonlyonecommonfactor.

2and6 3and8 15and12

9and11 49and21 15and22

Whatdoyounotice?

6

DoyouagreewithMo?

Explainyourreasoning.

Whydoyouthinkthishappens?

7 a) Listthefactorsof60inorderfromlowesttohighest.

b) Listthefactorsof84inorderfromsmallesttogreatest.

c) Whatisthehighestcommonfactorof60and84?

8 Whitneybakes24cakes.

Dexterbakes30cakes.

Boxescanhold2,3,4,5,6or10cakes.

WhitneyandDexterwanttosharetheircakesequallyintoboxes.

a) WhichboxescouldWhitneyuse?

b) WhichboxescouldDexteruse?

c) Whichboxescouldtheybothuse?

Compareanswerswithapartner.

9

WhatarethetwonumbersthatTeddyisthinkingof?

and

15

9

20

10

All the factors of 36 are common factors

of 36 and 72 I am thinking of two numbers between 70 and 80.

The common factors are 1, 2, 4 and 8