10 ACMNA073 Number and place value • Apply place value to partition, rearrange and regroup numbers to at least tens of thousands to assist calculations and solve problems. ACMNA083 Patterns and algebra • Use equivalent number sentences involving addition and subtraction to find unknown quantities.

1 JerryandJosiefinishedtheirmathstests.

a Marktheirwork. bGiveeachofthemamark. c Rewritetheonesthatarewrongandworkoutthecorrectanswer.

2 Completethesenumberpatterns.

a 7–2=______ b 9–4=______ c 8–3=______ d 9–7=______

70–20=______ 90–______=______ ______–______=______ ______–______=______

700–200=______ 900–______=______ ______–______=______ ______–______=______

e 5–2=3 f 7–4=______ g 8–4=______ h 6–3=______

15–2=______ 17–4=______ 18–4=______ 16–3=______

25–2=______ 27–4=______ 28–4=______ 26–3=______

85–2=______ 67–4=______ 58–4=______ 96–3=______

Two-digit subtractionTwo-digit subtraction

64–31______________

72–30______________3 3 4 0

99–63______________

59–15______________3 5 4 4

36–15______________

47–27______________2 1 2 7

Josie78

–23______________

69–15______________4 5 5 4

85–23______________

77–45______________6 2 4 2

59–27______________

48–16______________2 2 3 2

Jerry

Mark__________ Mark__________

ghost houseLab 4Lab 4

2-digit algorithms

11ACMNA073 Number and place value • Apply place value to partition, rearrange and regroup numbers to at least tens of thousands to assist calculations and solve problems. ACMNA083 Patterns and algebra • Use equivalent number sentences involving addition and subtraction to find unknown quantities.

5 FarmerFredhad64sheep.Howmanywereleftwhenhesold39?

6 Carolhad880jellybeans.Shewassickwhensheate132.Howmanywereleft?

1 UsestrategyA.

a 53–28=____________________ b 64–29=64–_____+_____

=_____ =_____

c 46–19=46–_____+_____ d 85–57=85–_____+_____

=_____ =_____

e 97–68=97–_____+_____ f 73–36=73–_____+_____

=_____ =_____

2 UsestrategyB.

a 67–43=67–40–3 b 91–52=91–_____–_____

=_____ =_____

c 52–24=52–_____–_____ d 75–31=75–_____–_____

=_____ =_____

e 80–33=80–_____–_____ f 41–24=41–_____–_____

=_____ =_____

3

a

b

4

a

b

Subtraction strategiesSubtraction strategies

StrategyA64–18=64–20+2=46

StrategyB71–24=71–20–4=47

Partition91is90and1.Takeaway90

thentakeawayanother1.

Checkanswersbycountingon.

27–

38

7356 64 49 76 62 81 50

32–

53

9161 70 62 87 74 90 83

Challenge!Makeupasubtractionproblemaboutkiteswheretheansweris37.

53-30+2

Mixed

12 ACMNA073 Number and place value • Apply place value to partition, rearrange and regroup numbers to at least tens of thousands to assist calculations and solve problems. ACMNA083 Patterns and algebra • Use equivalent number sentences involving addition and subtraction to find unknown quantities.

Subtraction on a number lineSubtraction on a number line Touseanumberlineforsubtractionstartfromtheright.72–37Youcanuselittlejumps

orbigjumps.

53

71

85

1 a 16–9=________ b 15–8=________

c 14–6=________ d 12–7=________

e 11–5=________ f 16–8=________

g 15–9=________ h 13–6=________

i 14–5=________ j 17–8=________

2 Usethenumberlines.

a 53–26=________

b 71–43=________

c 85–37=________

d 92–48=________

e 80–35=________

f 264–149=_______

g 376–123=_______

h 457–243=_______

3 Jinlovesolives.Hehad73jarsinthepantry.Thievesbrokeinandstole47jars.

a Howmanydidhehaveleft?________

b Howdidyouworkoutyouranswer?________________________________________________________

__________________________________________________________________________________________________

c Showanotherway.___________________________________________________________________________

d Whichwaywasbest?_____________________

e Howcanyoucheckifyouarecorrect?_____________________________________________________

Strategies –

–1 –10

7262524235

–1 –1 –5 –30

35 37 42 72

13ACMNA073 Number and place value • Apply place value to partition, rearrange and regroup numbers to at least tens of thousands to assist calculations and solve problems. ACMNA080 Money and financial mathematics • Solve problems involving purchases and the calculation of change to the nearest five cents with and without digital technologies.

3-digit subtraction

2 Changefrom$1?

3

Three-digit subtractionThree-digit subtraction

WorkbackwardsIfIsubtract13fromanumber,thendoubletheanswer,Iget28.

Whatisthenumber?

1 Usethehundredsquaretohelp.

a 100–56=________,56+________=100

b 100–23=________,23+________=100

c 100–49=________,49+________=100

d 100–64=________,64+________=100

e 100–11=________,11+________=100

f 100–77=________,77+________=100

a 346–125_________

_________

b 877–542_________

_________

c 539–413_________

_________

d 621–320_________

_________

e 959–426_________

_________

f 148–23__________________

g 273–153_________

_________

h 759–532_________

_________

i 485–165_________

_________

j 907–506_________

_________

k 986–144_________

_________

l 890–770_________

_________

m 679–238_________

_________

n 748–341_________

_________

o 485–21__________________

83c

37c

45c

68c

79c

a c e

b d

14

Problem solvingProblem solving

ACMNA073 Number and place value • Apply place value to partition, rearrange and regroup numbers to at least tens of thousands to assist calculations and solve problems. ACMNA083 Patterns and algebra • Use equivalent number sentences involving addition and subtraction to find unknown quantities.14

Work backwards, use a table

Fourchildrenbroughthomefishfordinner.Tamcaughtthesmallestfish,25cmshorterthanGrace’s.Grace’sfishwas10cmlongerthanTeddy’s.Teddy’sfishwas12cmlongerthanHarry’sfish,whichwas25cmlong.Howlongweretheotherfish?

HarryTeddyGraceTam

Harry’sfish=25cm

Teddy’sfish=25+12=_____________

Grace’sfish=__________________________

Tam’sfish=____________________________

Checkbackwards:22+25–________–________=________cm=Harry’sfish

1 ThetemperatureinDubboonWednesdaywas5degreeshigherthaninWellington.Wellingtonwas8degreescoolerthanParkes,whichwas2degreeshotterthanForbes.Forbes’temperaturewas34degrees,sowhattemperatureswerereportedattheothertowns?

Forbes=________________________________

Parkes=________________________________

Wellington=___________________________

Dubbo=________________________________

2 Inthemathstest,Deegainedabetterscorethanlastweek,butstill10lessthanKay.Kay’sscorewas5lessthanherfriend,Len.Lengained12morethanRod,whoscored85.Whosemarkwashighestandwhatweretheother’sscores?

______________________________________________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________

3 Writeyourownproblemwiththisending.Pete’s house is 32 km from school. Who lives farthest from school?

______________________________________________________________________________________________________

______________________________________________________________________________________________________

______________________________________________________________________________________________________