1. $169+76+24+831= (169+831)+(76+24)$,这里(
A.只运用了加法交换律
B.只运用了加法结合律
C.运用了加法交换律和加法结合律
C
)。A.只运用了加法交换律
B.只运用了加法结合律
C.运用了加法交换律和加法结合律
答案:
C
2. $125× 4× 25× 8$的简便算法是(
A.$(125× 8)× (4× 25)$
B.$125× 8+(4× 25)$
C.$(125× 25)× (4× 8)$
A
)。A.$(125× 8)× (4× 25)$
B.$125× 8+(4× 25)$
C.$(125× 25)× (4× 8)$
答案:
A
3. $792× 99= 792× 100◯ 792× 1$,$◯$里应该填(
A.$+$
B.$-$
C.$×$
B
)。A.$+$
B.$-$
C.$×$
答案:
B
4. 三个数相乘,先乘前两个数再乘第三个数,或者先乘后两个数再乘第一个数,积不变,这叫作乘法(
A.结合律
B.交换律
C.分配律
A
)。A.结合律
B.交换律
C.分配律
答案:
A
5. 与$a× 8-b× 8$相等的式子是(
A.$(a+b)× 8$
B.$(a-b)× (8+8)$
C.$(a-b)× 8$
C
)。A.$(a+b)× 8$
B.$(a-b)× (8+8)$
C.$(a-b)× 8$
答案:
C
6. 下面算式的结果与$25× 24$的结果不相等的是(
A.$25× 4× 6$
B.$25× 4+25× 6$
C.$25× 20+25× 4$
B
)。A.$25× 4× 6$
B.$25× 4+25× 6$
C.$25× 20+25× 4$
答案:
B
1. 口算。(4分)
$15× 11= $
$200÷ 5÷ 4= $
$15× 11= $
165
$240÷ 6= $40
$180-79-21= $80
$25× 13× 4= $1300
$200÷ 5÷ 4= $
10
$480÷ 3÷ 8= $20
$125× 3× 8= $3000
$16× 25= $400
答案:
1. $15× 11= 165$
2. $240÷ 6= 40$
3. $180-79-21= 80$
4. $25× 13× 4= 1300$
5. $200÷ 5÷ 4= 10$
6. $480÷ 3÷ 8= 20$
7. $125× 3× 8= 3000$
8. $16× 25= 400$
2. $240÷ 6= 40$
3. $180-79-21= 80$
4. $25× 13× 4= 1300$
5. $200÷ 5÷ 4= 10$
6. $480÷ 3÷ 8= 20$
7. $125× 3× 8= 3000$
8. $16× 25= 400$
2. 脱式计算。(12分)
$816÷ 8× 12+172$ $400÷ [(160-120)÷ 8]$
$(460+150)× (240-204)$ $300-[6× (30-27)]$
$20× [(982-100)÷ 9]$ $[46+(128-24)]÷ 5$
$816÷ 8× 12+172$ $400÷ [(160-120)÷ 8]$
$(460+150)× (240-204)$ $300-[6× (30-27)]$
$20× [(982-100)÷ 9]$ $[46+(128-24)]÷ 5$
答案:
1.
$816 ÷ 8 × 12 + 172$
$= 102 × 12 + 172$
$= 1224 + 172$
$= 1396$
2.
$400 ÷ [(160 - 120) ÷ 8]$
$= 400 ÷ [40 ÷ 8]$
$= 400 ÷ 5$
$= 80$
3.
$(460 + 150) × (240 - 204)$
$= 610 × 36$
$= 21960$
4.
$300 - [6 × (30 - 27)]$
$= 300 - [6 × 3]$
$= 300 - 18$
$= 282$
5.
$20 × [(982 - 100) ÷ 9]$
$= 20 × [882 ÷ 9]$
$= 20 × 98$
$= 1960$
6.
$[46 + (128 - 24)] ÷ 5$
$= [46 + 104] ÷ 5$
$= 150 ÷ 5$
$= 30$
$816 ÷ 8 × 12 + 172$
$= 102 × 12 + 172$
$= 1224 + 172$
$= 1396$
2.
$400 ÷ [(160 - 120) ÷ 8]$
$= 400 ÷ [40 ÷ 8]$
$= 400 ÷ 5$
$= 80$
3.
$(460 + 150) × (240 - 204)$
$= 610 × 36$
$= 21960$
4.
$300 - [6 × (30 - 27)]$
$= 300 - [6 × 3]$
$= 300 - 18$
$= 282$
5.
$20 × [(982 - 100) ÷ 9]$
$= 20 × [882 ÷ 9]$
$= 20 × 98$
$= 1960$
6.
$[46 + (128 - 24)] ÷ 5$
$= [46 + 104] ÷ 5$
$= 150 ÷ 5$
$= 30$
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