题目内容
能简算的要简算
99×
| (1.25+
| ||||||||
| 3.6×42.3×3.75-12.5×0.423×28． |
（1）99×
-
，
=（98+1）×
-
，
=99+
-
，
=99+（
-
），
=99+1，
=100；
（2）（1.25+
）×8×
，
=（1
+
）×8×
，
=
×8×
，
=
；
（3）
+
+
+…+
，
=
-
+
-
+
-
+…+
-
，
=
，
=
；
（4）3.6×42.3×3.75-12.5×0.423×28，
=0.9×4×42.3×3.75-0.125×42.3×7×4，
=0.9×42.3×4×3.75-0.125×4×42.3×7，
=0.9×42.3×15-0.5×42.3×7，
=42.3×（0.9×15-0.5×7），
=42.3×（13.5-3.5），
=42.3×10，
=423．
| 99 |
| 98 |
| 1 |
| 98 |
=（98+1）×
| 99 |
| 98 |
| 1 |
| 98 |
=99+
| 99 |
| 98 |
| 1 |
| 98 |
=99+（
| 99 |
| 98 |
| 1 |
| 98 |
=99+1，
=100；
（2）（1.25+
| 7 |
| 8 |
| 7 |
| 34 |
=（1
| 1 |
| 4 |
| 7 |
| 8 |
| 7 |
| 34 |
=
| 17 |
| 8 |
| 7 |
| 34 |
=
| 7 |
| 2 |
（3）
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 4×5 |
| 1 |
| 99×100 |
=
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 99 |
| 1 |
| 100 |
=
| 1 |
| 2 |
| 1 |
| 100 |
=
| 49 |
| 100 |
（4）3.6×42.3×3.75-12.5×0.423×28，
=0.9×4×42.3×3.75-0.125×42.3×7×4，
=0.9×42.3×4×3.75-0.125×4×42.3×7，
=0.9×42.3×15-0.5×42.3×7，
=42.3×（0.9×15-0.5×7），
=42.3×（13.5-3.5），
=42.3×10，
=423．
练习册系列答案
阅读快车系列答案
相关题目