题目内容
脱式计算,能简算的要简算.
| 12.4-2.4×3.75÷2.5 | ||||||||
2.5×
| 1999+999×999. |
(1)
+
×
+
÷4,
=
+
×
+
×
,
=(1+
+
)×
,
=2×
,
=
;
(2)12.4-2.4×3.75÷2.5,
=12.4-9÷2.5,
=12.4-3.6,
=8.8;
(3)2.5×
-0.21÷
+9.63,
=1-0.63+9.63,
=1+(9.63-0.63),
=1+9,
=10;
(4)1999+999×999,
=1000+999+999×999,
=1000+999×(1+999),
=1000+999×1000,
=1000×(1+999),
=1000×1000,
=1000000.
| 1 |
| 4 |
| 2 |
| 7 |
| 1 |
| 4 |
| 5 |
| 7 |
=
| 1 |
| 4 |
| 2 |
| 7 |
| 1 |
| 4 |
| 5 |
| 7 |
| 1 |
| 4 |
=(1+
| 2 |
| 7 |
| 5 |
| 7 |
| 1 |
| 4 |
=2×
| 1 |
| 4 |
=
| 1 |
| 2 |
(2)12.4-2.4×3.75÷2.5,
=12.4-9÷2.5,
=12.4-3.6,
=8.8;
(3)2.5×
| 2 |
| 5 |
| 1 |
| 3 |
=1-0.63+9.63,
=1+(9.63-0.63),
=1+9,
=10;
(4)1999+999×999,
=1000+999+999×999,
=1000+999×(1+999),
=1000+999×1000,
=1000×(1+999),
=1000×1000,
=1000000.
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