题目内容
递等式计算．（能简算的要简算，并写出主要的简算过程）
①4×0.8×2.5×12.5
②
÷[1-（
+
）]
③（2.8+3.85÷3.5）×4.6
④6.5×1.83+0.17×6.5．
①4×0.8×2.5×12.5
②
| 2 |
| 15 |
| 1 |
| 5 |
| 1 |
| 3 |
③（2.8+3.85÷3.5）×4.6
④6.5×1.83+0.17×6.5．
①4×0.8×2.5×12.5，
=（4×2.5）×（0.8×12.5），
=10×10，
=100；
②
÷[1-（
+
）]，
=
÷[1-
]，
=
÷
，
=
×
，
=
；
③（2.8+3.85÷3.5）×4.6，
=（2.8+1.1）×4.6，
=3.9×4.6，
=（4-0.1）×4.6，
=4×4.6-0.1×4.6，
=18.4-0.46，
=17.94；
④6.5×1.83+0.17×6.5，
=（1.83+0.17）×6.5，
=2×6.5，
=13．
=（4×2.5）×（0.8×12.5），
=10×10，
=100；
②
| 2 |
| 15 |
| 1 |
| 5 |
| 1 |
| 3 |
=
| 2 |
| 15 |
| 8 |
| 15 |
=
| 2 |
| 15 |
| 7 |
| 15 |
=
| 2 |
| 15 |
| 15 |
| 7 |
=
| 2 |
| 7 |
③（2.8+3.85÷3.5）×4.6，
=（2.8+1.1）×4.6，
=3.9×4.6，
=（4-0.1）×4.6，
=4×4.6-0.1×4.6，
=18.4-0.46，
=17.94；
④6.5×1.83+0.17×6.5，
=（1.83+0.17）×6.5，
=2×6.5，
=13．
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