Simple Calculation Operation Properties abba Commutative law of

Simple Calculation

Operation Properties a+b=b+a Commutative law of addition Commutative law of multiplication a×b=b×a Associative law of addition (a+b)+c=a+(b+c) Associative law of multiplication (a×b)×c=a×(b×c) Property of division a÷b÷c=a÷ (b×c) (b and c ≠ 0) Distributive law of multiplication (a+b)×c=a×c+b×c

Fill in the brackets ÷ ÷ （1）5600÷（56× 25）＝ 5600 56 25 7 10 （2）（10+7）× 9= × 9+ × 9 82 18 （3） 18 + 64 +82=64 +（ + ） 125 8 （4） 125 × 9 × 8= × × 9 24 4 （5）37× 24 -37× 4=37×（ － ）

True or False? （1）7200÷ 24÷ 3 = 7200÷（24× 3）（ ）√ √ 246÷（2× 3） （3）125× 71× 8 = (125× 8)×(71× 8) （ ）× （2）246÷ 6 = 246÷ 2÷ 3 （ ） 125× 8× 7

Choose (1)Which answer is the same with 24× 12+24 × 1 A)24×（12+24） B)24× 12+24× 24 C)24×（12+1）

Fill in the bracket （A+B）×C=28，B×C=7 A×C=( ) （A+B）×C= 28 A ×C+B ×C= 28 21 7

BOYS: GIRLS： 100+100= 200 49+57= 106 600 -300= 300 124 -76= 48 30 + 40 = 70 36+48= 84

Make tens 10 1 9 2 8 3 7 4 6 5 5

Game I say “ 1” You say “ 9”

10 5 + 7 + 5 = 17 10 4 + 6 + 9 = 19 20 2 + 13 + 7 = 22 20 1 + 10 + 19 = 30 30 22 + 14 + 8 = 44

Make hundreds 9 10 6 1 3 9 +（ ） 1 0 0 7 9 10 3 4 5 5 +（ ） 8 0 0 3 9 10 1 2 8 2 7 2 + （ ） 4 0 0

Make hundreds 59 159－（ ）=100 26 126－（ ）=100 18 218－（ ）=200 33 633－（ ）=600 79 879－（ ）=800

Make hundreds 25× 4=100 100÷ 4=25 50× 2=100 100÷ 25=4 125× 8=1000 1000÷ 8=125

Can we calculate the following simply? 500 (1) 155 + 846 + 345 ( ) √ 100 (2) 25× 8× 4 ( ) √ (3) 117 + 484 + 329 ( ) x (4) 36× 101 ( ) √ =36×(100+1) =36× 100+36× 1

139+261 (1) 139+261 =(139+261)+239 =400+239 =639 (2) 139+261 =139+(239+261) =139+500 =639

25× 32 (1) 25× 32 =25×（4× 8） =（25× 4）× 8 =100× 8 =800 (2) 25× 32 =25×（30+2） =25 × 30+25 × 2 =750+50 =800

Change a number in order to simply calculate 54× 28＋46× 71 54× 28＋46× 28 54× 71＋46× 71 46× 28＋46× 71