题目内容
怎样简便就怎样算.
×18×
×
+
×
24×
×
×21
×39
2006×
×
+
×
.
| 3 |
| 5 |
| 5 |
| 9 |
| 6 |
| 7 |
| 2 |
| 5 |
| 2 |
| 5 |
| 9 |
| 7 |
24×
| 2 |
| 7 |
| 5 |
| 12 |
| 39 |
| 40 |
2006×
| 2004 |
| 2005 |
| 5 |
| 2 |
| 7 |
| 8 |
| 7 |
| 8 |
| 11 |
| 2 |
(1)
×18×
=
×(18×
)
=
×10
=6;
(2)
×
+
×
=(
+
)×
=
×
=
(3)24×
×
×21
=(21×
)×(
×24)
=6×10
=60;
(4)
×39
=
×(40-1)
=
×40-
=39-
=38
;
(5)2006×
=(2005+1)×
=2005×
+
=2004+
=2004
;
(6)
×
+
×
=(
+
)×
=8×
=7.
| 3 |
| 5 |
| 5 |
| 9 |
=
| 3 |
| 5 |
| 5 |
| 9 |
=
| 3 |
| 5 |
=6;
(2)
| 6 |
| 7 |
| 2 |
| 5 |
| 2 |
| 5 |
| 9 |
| 7 |
=(
| 6 |
| 7 |
| 9 |
| 7 |
| 2 |
| 5 |
=
| 15 |
| 7 |
| 2 |
| 5 |
=
| 6 |
| 7 |
(3)24×
| 2 |
| 7 |
| 5 |
| 12 |
=(21×
| 2 |
| 7 |
| 5 |
| 12 |
=6×10
=60;
(4)
| 39 |
| 40 |
=
| 39 |
| 40 |
=
| 39 |
| 40 |
| 39 |
| 40 |
=39-
| 39 |
| 40 |
=38
| 1 |
| 40 |
(5)2006×
| 2004 |
| 2005 |
=(2005+1)×
| 2004 |
| 2005 |
=2005×
| 2004 |
| 2005 |
| 2004 |
| 2005 |
=2004+
| 2004 |
| 2005 |
=2004
| 2004 |
| 2005 |
(6)
| 5 |
| 2 |
| 7 |
| 8 |
| 7 |
| 8 |
| 11 |
| 2 |
=(
| 5 |
| 2 |
| 11 |
| 2 |
| 7 |
| 8 |
=8×
| 7 |
| 8 |
=7.
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