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怎样算简便就怎样算.(1)12.74-18

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怎样算简便就怎样算.
(1)12.74-
1
8
(1)12.74-
1
8+2.26-9.875,
=12.74-0.125+2.26-9.875,
=(12.74+2.26)-(0.125+9.875),
=15-10,
=5;
(2)4.8×3.9+6.1×4
4
5,
=4.8×3.9+6.1×4.8,
=4.8×(3.9+6.1),
=4.8×10,
=48;
(3)(2.5-3.2×
5
16)÷(4
8
15÷3.4),
=(2.5-1)÷(
68
15×
5
17),
=1.5÷
4
3,
=
3

3
4,
=
9
8;
(4)18÷[
5
6+(
5
8-
1
3)],
=18÷[
5
6+
5
8-
1
3],
=18÷[
5
6-
1
3+
5
8],
=18÷[
1
2+
5
8],
=18÷
9
8,
=16.