推荐回答(2个)
一、仔细想,认真填。(每空1分,共25分)
1、用字母ɑ、b、c表示下面运算定律:
(1)加法交换律:_______________;(2)乘法分配律:_______________;
(3)乘法交换律:_______________;(4)加法结合律:_______________;
(5)乘法结合律:_______________。
2、任意两个相乘,交换两个因数 ,积不变,这叫_________。
3、任意三个数相加,先把_________相加或先把_________相加,和不变,这叫加法结合律。
4、两个数的_________与一个数相乘,可以先把它们分别与这个数_________,再相_________,结果不变,这叫_________。
5、一个数连续减去两个减数,等于用这个数减去这两个减数的_________。
6、一个数连续除以几个数,任意_________除数的位置,商不变。即ɑ÷b÷c=_________.
7、45×(20×39)=(45×20)×39 这是应用了_________律。
8、用简便方法计算376+592+24,要先算_________,这是根据_________律。
9、根据运算定律,在□里填上适当的数,在○里填上适当的运算符号。
(1)a+(30+8)=(□+□)+8
(2)45×□=32×□
(3)25×(8-4)=□ ×□ ○□ × □
(4)496-120-230=496-( □ ○□ )
(5)375-(25+50)=375- □ ○ □
二、对号入座。(把正确的答案的序号填在括号里)(10分)
1.49×25×4=49×(25×4)这是根据( )。
A. 乘法交换律 B.乘法分配律
C.乘法结合律 D.加法结合律
2.986-299的简便算法是( )。
A.986-300-1 B.986-300+1
C.986-200-99 D.986-(300+1)
3.32+29+68+41=32+68+(29+41)这是根据( )。
A.加法交换律 B.加法结合律
C.加法交换律和结合律 D.乘法结合律
4.下面算式中( )运用了乘法分配律。
A.42×(18+12)=424×30
B.a×b+a×C=a×(b-C)
C.4×a×5=a×(4×5)
D.(125-50)×8=125×8-50×8
5、125÷25×4的简便算法是( )
A、125÷(25×4) B、125×4÷25
C、125÷5×5×4 D、125÷5÷5×4
三、判断。(对的在括号里面打“√”,错的打“×” )(10分)
1、25×(4+8)=25×4+2×58…………………………………………( )
2、(32+4)×25=32+4×25 …………………………………………… ( )
3、180÷5÷4=180÷(5×4)……………………………………………( )
4、125×4×25×8=(125×8)+(4×25)…………………………… ( )
5、52+83+48=83+(52+48)这一步计算只运用了加法交换律。………( )
6、31+23+77=31+100………………………………………………… ( )
7、136-68+32=136-(68+32)………………………………………( )
8、412+78+22=412+(78+22)………………………………………( )
9、17×99+1=17×100……………………………………………………( )
10、450×8÷100=450×100÷8………………………………………… ( )
四、用简便方法计算下面各题(12×3=36分)
(1)94+38+106+62
(2) 125×15×8
(3) 25×32×125
(4)125÷25×8
(5) 125×48
(6)989-186-14
(7)4600÷25÷4
(8)136×101-136
(9) 32×37+47×37+21×37
(10)99×77+77
(11) 99×8
(12) 78×37-37×68
五、解决问题,能简便的就简便计算。(19分)
1、同学们去军区演出,四年级去113人,五年级去272人,六年级去87人。三个年级一共去多少人?(3分)
2、粮店运进一批大米,大、小袋各16袋,大袋每袋50千克,小袋每袋25千克。一共运进大米多少千克?(4分)
3、一个工程队要用一个月的时间挖一条长2670米的水渠,已知上旬挖了1016米,中旬挖了984米。要想按期完成任务,下旬需要挖多少米?(4分)
4、学校要做4800面彩旗,把这个任务交给25个班,每个班有4个小组,平均每个小组要做多少面彩旗?(4分)
5、一座大楼有25层,每层有24个窗口,每个窗口有4块玻璃,这座大楼一共有多少块玻璃?(4分)
2061-(319+661)
643+899-199
162×59-162×47
89+18×38
168÷3-168÷4
28000÷32÷125×170
25×72-1201
5×16×125
970+(437+330)
2324+305+2676
32×17×25
4200÷60÷5
2098-497
86×28-7
10800÷(18×4)
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