Add and subtract fractions (2)

1 Amirisusingfractionstripstoworkout 23

+ 14

Amirsaysheneedstofindacommondenominator.

a) CompleteAmir’smethod.

23

=12

14

=12

23

+ 14=

12 + 12 = 12

b) Showtheadditiononthefractionstrip.

c) Couldyouhaveusedadifferentdenominator?

2 Whatcommondenominatorcanyouusetoaddthefractions?

a) 25

+ 12

Commondenominator=

b) 23

+ 45

Commondenominator=

c) 78

– 14

Commondenominator=

d) 79

– 16

Commondenominator=

e) 1115

+ 310

Commondenominator=

3 RonandEvaareworkingout 14

+ 56

Ron’s method Eva’s method

a) WhatisthesameaboutRon’sandEva’smethods?

b) Whatisdifferentabouttheirmethods?

c) Whichmethoddoyouprefer?Why?

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14 + 5

6 = 312 + 10

12 = 1312

14 + 5

6 = 624 + 20

24 = 2624

4 Completethecalculations.

a) 15

+ 34

= c) 12

– 17

=

b) 78

– 13

= d) 1118

+ 712

=

5 Moisdrawingjumpsonanumberline.

Thejumpsarethesamesize.

a) Whatisthesizeofthejump?

b) WhatisthevalueofA?

6 Completethebarmodel.

518

16

59

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7 Completetheadditions.

Giveyouranswersasmixednumbersandasimproperfractions.

a) 45

+ 54

= = c) 98

+ 89

= =

b) 23

+ 32

= = d) = = 53

+ 35

Whatpatternsdoyounotice?

8 Lookattheseadditions.

a) Whendoesthispatternfirstgiveananswergreaterthan2?

b) Doyouthinkthepatternwillevergiveananswergreater

than100?

15

13

A12

+ 13

= 12

+ 13

+ 14

= 12

+ 13

+ 14

+ 15

=