Question

怎么简便怎样算 (1)4.5+5.5×6.9 (2)2.4×9.9(3)2.5×0.32×1.25？

Answer 1

(1) 4.5+5.5×6.9
=4.5+5.5×(7-0.1)
=4.5+5.5×7-5.5×0.1
=4.5+38.5-0.55
=43-0.55
=45.45
(2)2.4×9.9
=2.4×(10-0.1)
=2.4×10-2.4×0.1
=24-0.24
=23.76
(3)2.5×0.32×1.25
=2.5×0.4×0.8×1.25
=(2.5×0.4)×(0.8×1.25)
=1×1
=1
备注：第(1)小题如果非要简便，只能像上述一样计算，否则，常规脱式计算即可。