脱式计算(能简算的要简算)20.9+10.5÷(5.2-3.5);3.5×0.7+5.5×0.7+0.7;10.64+7.65×2.4+11.76; 6.2×9.9.
第1个回答 2014-09-25
(1)20.9+10.5÷(5.2-3.5)
=20.9+10.5÷1.7
=20.9+6
=27
;
(2)3.5×0.7+5.5×0.7+0.7
=(3.5+5.5+1)×0.7
=10×0.7
=7;
(3)10.64+7.65×2.4+11.76
=10.64+18.36+11.76
=29+11.76
=40.76;
(4)6.2×9.9
=6.2×(10-0.1)
=6.2×10-6.2×0.1
=62-0.62
=61.38.
=20.9+10.5÷1.7
=20.9+6
3 |
17 |
=27
13 |
170 |
(2)3.5×0.7+5.5×0.7+0.7
=(3.5+5.5+1)×0.7
=10×0.7
=7;
(3)10.64+7.65×2.4+11.76
=10.64+18.36+11.76
=29+11.76
=40.76;
(4)6.2×9.9
=6.2×(10-0.1)
=6.2×10-6.2×0.1
=62-0.62
=61.38.
第2个回答 2015-02-14
2.3*7.5-3.5*5.5