用简便方法计算.(写出简算过程)(1)99×101 (2)12×(14+16-13) (3)1316×511+516×311.
(1)99×101
=99×(100+1)
=99×100+99×1
=9900+99
=9999;
(2)12×(
+
-
)
=12×
+12×
-12×
=3+2-4
=1;
(3)
×
+
×
=
×
+
×
=
×(
+
)
=
×
=
.
=99×(100+1)
=99×100+99×1
=9900+99
=9999;
(2)12×(
1 |
4 |
1 |
6 |
1 |
3 |
=12×
1 |
4 |
1 |
6 |
1 |
3 |
=3+2-4
=1;
(3)
13 |
16 |
5 |
11 |
5 |
16 |
3 |
11 |
=
5 |
16 |
13 |
11 |
5 |
16 |
3 |
11 |
=
5 |
16 |
13 |
11 |
3 |
11 |
=
5 |
16 |
16 |
11 |
=
5 |
11 |
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