题目内容
能简便计算要简便计算.
×3.5+5.5×80%+0.8;
999
+99
+9
+
;
34
×24+66
×24-47
÷
;
[1
+(6
-3.75)×2
]÷3
;
.
4 |
5 |
999
8 |
9 |
8 |
9 |
8 |
9 |
1 |
3 |
34
1 |
3 |
1 |
3 |
2 |
3 |
1 |
24 |
[1
1 |
4 |
2 |
3 |
1 |
7 |
3 |
4 |
1×2+2×4+3×6+4×8+5×10 |
2×3+4×6+6×9+8×12+10×15 |
考点:分数的巧算
专题:计算问题(巧算速算)
分析:(1)运用乘法分配律简算;
(2)
=1-
,由此先把带分数化成整千、整百数、整十数减去
,再利用加法结合律和减法的性质简算;
(3)先把除法变成乘法,再运用乘法分配律简算;
(4)先算小括号里面的减法,再算中括号里面的乘法,然后算中括号里面的加法,最后算括号外的除法;
(5)先把分母提出公因数3,再约分即可求解.
(2)
8 |
9 |
1 |
9 |
1 |
9 |
(3)先把除法变成乘法,再运用乘法分配律简算;
(4)先算小括号里面的减法,再算中括号里面的乘法,然后算中括号里面的加法,最后算括号外的除法;
(5)先把分母提出公因数3,再约分即可求解.
解答:
解:(1)
×3.5+5.5×80%+0.8
=0.8×(3.5+5.5+1)
=0.8×10
=8;
(2)999
+99
+9
+
=(1000-
)+(100-
)+(10-
)+(
×3)
=(1000+100+10)+(
×3-
×3)
=1110+0
=1110;
(3)34
×24+66
×24-47
÷
=34
×24+66
×24-47
×24
=(34
+66
-47
)×24
=53×24
=1272;
(4)[1
+(6
-3.75)×2
]÷3
=[1
+
×
]÷3
=[1
+
]÷3
=
×
=2;
(5)
=
=
.
4 |
5 |
=0.8×(3.5+5.5+1)
=0.8×10
=8;
(2)999
8 |
9 |
8 |
9 |
8 |
9 |
1 |
3 |
=(1000-
1 |
9 |
1 |
9 |
1 |
9 |
1 |
9 |
=(1000+100+10)+(
1 |
9 |
1 |
9 |
=1110+0
=1110;
(3)34
1 |
3 |
1 |
3 |
2 |
3 |
1 |
24 |
=34
1 |
3 |
1 |
3 |
2 |
3 |
=(34
1 |
3 |
1 |
3 |
2 |
3 |
=53×24
=1272;
(4)[1
1 |
4 |
2 |
3 |
1 |
7 |
3 |
4 |
=[1
1 |
4 |
35 |
12 |
15 |
7 |
3 |
4 |
=[1
1 |
4 |
25 |
4 |
3 |
4 |
=
30 |
4 |
4 |
15 |
=2;
(5)
1×2+2×4+3×6+4×8+5×10 |
2×3+4×6+6×9+8×12+10×15 |
=
1×2+2×4+3×6+4×8+5×10 |
3×(2×1+4×2+6×3+8×4+10×5) |
=
1 |
3 |
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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