1. 应用运算律填空,并说一说应用了什么运算律。
(1)$62\times\square = 58\times\square$ ( )
(2)$25\times(4\times76)=(\square\times\square)\times76$ ( )
(3)$4\times8\times5\times125=(4\times\square)\times(\square\times\square)$ ( )
(4)$76\times102 = 76\times\square+\square\times2$ ( )
(1)$62\times\square = 58\times\square$ ( )
(2)$25\times(4\times76)=(\square\times\square)\times76$ ( )
(3)$4\times8\times5\times125=(4\times\square)\times(\square\times\square)$ ( )
(4)$76\times102 = 76\times\square+\square\times2$ ( )
答案:
(1)58 62 乘法交换律(2)25 4 乘法结合律(3)5 8 125 乘法交换律和结合律(4)100 76 乘法分配律
2. 算一算,比一比。
$25\times28 =$ $24\times15 =$ $58\times98 =$
$25\times4\times7 =$ $6\times(4\times15) =$ $58\times100 - 58\times2 =$
$25\times28 =$ $24\times15 =$ $58\times98 =$
$25\times4\times7 =$ $6\times(4\times15) =$ $58\times100 - 58\times2 =$
答案:
700 700 360 360 5684 5684
3. 用简便方法计算。
$25\times207$ $125\times5\times8\times6$ $46\times102 - 46\times2$
$25\times207$ $125\times5\times8\times6$ $46\times102 - 46\times2$
答案:
$25×207$
$=25×200 + 25×7$
$=5000 + 175$
$=5175$
$125×5×8×6$
$=(125×8)×(5×6)$
$=1000×30$
$=30000$
$46×102 - 46×2$
$=46×(102 - 2)$
$=46×100$
$=4600$
4. 某双层列车每节车厢的座位数和车厢节数如下表。该双层列车最多能坐多少名乘客?

答案:
$102×12 + 98×12 = 2400$(名)
或$(102 + 98)×12 = 2400$(名)
5. 用简便方法计算。
(1)$450\times28 + 720\times45$ (2)$888\times8 + 333\times12$
(1)$450\times28 + 720\times45$ (2)$888\times8 + 333\times12$
答案:
(1)$450×28 + 720×45$
$=45×280 + 720×45$
$=45×(280 + 720)$
$=45×1000$
$=45000$
(2)$888×8 + 333×12$
$=111×(8×8) + 111×(3×12)$
$=111×64 + 111×36$
$=111×(64 + 36)$
$=111×100$
$=11100$
口算乐园
$43\times3 =$ ____________
$55\div5 =$ ____________
$33\times7 =$ ____________
$80\div20 =$ ____________
$36\times4 =$ ____________
$45\div3 =$ ____________
$76 - 29 =$ ____________
$108 + 37 =$ ____________
$110 - 55 =$ ____________
$54 + 86 =$ ____________
$43\times3 =$ ____________
$55\div5 =$ ____________
$33\times7 =$ ____________
$80\div20 =$ ____________
$36\times4 =$ ____________
$45\div3 =$ ____________
$76 - 29 =$ ____________
$108 + 37 =$ ____________
$110 - 55 =$ ____________
$54 + 86 =$ ____________
答案:
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