题目内容
计算下面各题.(能用简算的用简算)
①100000÷32÷125÷25
②199999+19999+1999+199+19
③200.8×7.3-63×20.08
④888888×88888
⑤
+
+
+…+
+
⑥
.
①100000÷32÷125÷25
②199999+19999+1999+199+19
③200.8×7.3-63×20.08
④888888×88888
⑤
1 |
1×2 |
1 |
2×3 |
1 |
3×4 |
1 |
98×99 |
1 |
99×100 |
⑥
382+498×381 |
382×498-116 |
分析:①根据连除的性质进行计算;
②根据整数加法凑整法进行计算;
③根据乘法分配律进行计算;
④根据乘法分配律进行计算;
⑤根据分数的拆项进行计算;
⑥把分母根据乘法分配律进行计算,然后再约分即可.
②根据整数加法凑整法进行计算;
③根据乘法分配律进行计算;
④根据乘法分配律进行计算;
⑤根据分数的拆项进行计算;
⑥把分母根据乘法分配律进行计算,然后再约分即可.
解答:解:
①100000÷32÷125÷25,
=100000÷(32×125×25),
=100000÷(4×8×125×25),
=100000÷[(8×125)×(4×25)],
=100000÷[1000×100],
=100000÷100000,
=1;
②199999+19999+1999+199+19,
=(199999+1)+(19999+1)+(1999+1)+(199+1)+(19+1)-5,
=200000+20000+2000+200+20-5,
=222220-5,
=222215;
③200.8×7.3-63×20.08,
=20.08×73-63×20.08,
=20.08×(73-63),
=20.08×10,
=200.8;
④888888×88888,
=888888×(80000+8000+800+80+8),
=71111040000+7111104000+711110400+71111040+7111104,
=79011476544;
⑤
+
+
+…+
+
,
=1-
+
-
+
-
+…+
-
+
-
,
=1-
,
=
;
⑥
,
=
,
=
,
=
,
=1.
①100000÷32÷125÷25,
=100000÷(32×125×25),
=100000÷(4×8×125×25),
=100000÷[(8×125)×(4×25)],
=100000÷[1000×100],
=100000÷100000,
=1;
②199999+19999+1999+199+19,
=(199999+1)+(19999+1)+(1999+1)+(199+1)+(19+1)-5,
=200000+20000+2000+200+20-5,
=222220-5,
=222215;
③200.8×7.3-63×20.08,
=20.08×73-63×20.08,
=20.08×(73-63),
=20.08×10,
=200.8;
④888888×88888,
=888888×(80000+8000+800+80+8),
=71111040000+7111104000+711110400+71111040+7111104,
=79011476544;
⑤
1 |
1×2 |
1 |
2×3 |
1 |
3×4 |
1 |
98×99 |
1 |
99×100 |
=1-
1 |
2 |
1 |
2 |
1 |
3 |
1 |
3 |
1 |
4 |
1 |
98 |
1 |
99 |
1 |
99 |
1 |
100 |
=1-
1 |
100 |
=
99 |
100 |
⑥
382+498×381 |
382×498-116 |
=
382+498×381 |
(381+1)×498-116 |
=
382+498×381 |
381×498+498-116 |
=
382+498×381 |
381×498+382 |
=1.
点评:根据题意,找准巧算所运用的方法和运算定律,然后再进一步计算即可.
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