请问下面这几道题应该怎样简便计算?要具体的过程,(1)(1.6+1.6+1.6+1.6)×25(2)四又五分之二-(2.5+1.9)×(0.5—0.5)(3)四又五分之二-2.5+1.9×(0.5-0.5)(4)四又五分之二-2.5+1.9×0.5
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请问下面这几道题应该怎样简便计算?要具体的过程,(1)(1.6+1.6+1.6+1.6)×25(2)四又五分之二-(2.5+1.9)×(0.5—0.5)(3)四又五分之二-2.5+1.9×(0.5-0.5)(4)四又五分之二-2.5+1.9×0.5
请问下面这几道题应该怎样简便计算?要具体的过程,
(1)(1.6+1.6+1.6+1.6)×25
(2)四又五分之二-(2.5+1.9)×(0.5—0.5)
(3)四又五分之二-2.5+1.9×(0.5-0.5)
(4)四又五分之二-2.5+1.9×0.5—0.5
(5)[四又五分之二-(2.5+1.9×0.5)]—0.5
(6)[四又五分之二—(2.5+1.9)]×(0.5—0.5)
(7)[四又五分之二—(2.5+1.9)×0.5]—0.5
请问下面这几道题应该怎样简便计算?要具体的过程,(1)(1.6+1.6+1.6+1.6)×25(2)四又五分之二-(2.5+1.9)×(0.5—0.5)(3)四又五分之二-2.5+1.9×(0.5-0.5)(4)四又五分之二-2.5+1.9×0.5
(1)(1.6+1.6+1.6+1.6)×25
=1.6x4x25
=1.6x(4x25)
=1.6x100
=160
(2)四又五分之二-(2.5+1.9)×(0.5—0.5)
=四又五分之二-(2.5+1.9)×0
=四又五分之二-0
=四又五分之二
(3)四又五分之二-2.5+1.9×(0.5-0.5)
=四又五分之二-2.5+1.9×0
=四又五分之二-0
=四又五分之二
(4)四又五分之二-2.5+1.9×0.5—0.5
=4.4-2.5-0.95-0.5
=4.4-(2.5+0.5)-(1-0.05)
=4.4-3-1+0.05
=0.4+0.05
=0.45
(5)[四又五分之二-(2.5+1.9×0.5)]—0.5
=[4.4-(2.5+0.95)]—0.5
=4.4-2.5-0.95-0.5 ( 跟(4)一样了 )
=0.45
(6)[四又五分之二—(2.5+1.9)]×(0.5—0.5)
=[四又五分之二—(2.5+1.9)]×0
=0
(7)[四又五分之二—(2.5+1.9)×0.5]—0.5
=[4.4-4.4×0.5]—0.5
=[4.4-2.2]—0.5
=2.2-0.5
=1.7