题目内容
用递等式计算(能简算的要简算).
4
|
9999×36+6666×96 | ||||||||
12
|
3.14×3.2+5.8×3.14+3.14 | ||||||||
783×
|
1+2-3-4+5+6-7-8+…-1983-1984+1985+1986. |
(1)4
-2
+
,
=4
-2
+
,
=(4
+
)-2
,
=5
-2
,
=3
;
(2)9999×36+6666×96,
=3333×3×36+3333×2×96,
=3333×108+3333×192,
=3333×(108+192),
=3333×300,
=999900;
(3)12
-2
×3
÷2
,
=12
-
×
×
,
=
-
,
=
;
(4)3.14×3.2+5.8×3.14+3.14,
=3.14×(3.2+5.8+1),
=3.14×10,
=31.4;
(5)783×
-37.5%+21.8×3.75,
=783×0.375-0.375+218×0.375,
=(783-1+218)×0.375,
=1000×0.375,
=375;
(6)1+2-3-4+5+6-7-8+…-1983-1984+1985+1986,
=1+(2-3-4+5)+(6-7-8+9)…+(1982-1983-1984+1985)+1986,
=1+0+0…+1986,
=1987.
| 1 |
| 5 |
| 3 |
| 4 |
| 5 |
| 12 |
=4
| 12 |
| 60 |
| 36 |
| 60 |
| 25 |
| 60 |
=(4
| 12 |
| 60 |
| 25 |
| 60 |
| 36 |
| 60 |
=5
| 37 |
| 60 |
| 36 |
| 60 |
=3
| 1 |
| 60 |
(2)9999×36+6666×96,
=3333×3×36+3333×2×96,
=3333×108+3333×192,
=3333×(108+192),
=3333×300,
=999900;
(3)12
| 2 |
| 5 |
| 2 |
| 5 |
| 3 |
| 4 |
| 1 |
| 2 |
=12
| 2 |
| 5 |
| 12 |
| 5 |
| 15 |
| 4 |
| 2 |
| 5 |
=
| 62 |
| 5 |
| 18 |
| 5 |
=
| 44 |
| 5 |
(4)3.14×3.2+5.8×3.14+3.14,
=3.14×(3.2+5.8+1),
=3.14×10,
=31.4;
(5)783×
| 3 |
| 8 |
=783×0.375-0.375+218×0.375,
=(783-1+218)×0.375,
=1000×0.375,
=375;
(6)1+2-3-4+5+6-7-8+…-1983-1984+1985+1986,
=1+(2-3-4+5)+(6-7-8+9)…+(1982-1983-1984+1985)+1986,
=1+0+0…+1986,
=1987.
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