(1)2.5*32*0.125
=(2.5*4)*(8*0.125)
=10*1
=10
(2)3.5-7+6.5
=3.5+6.5-7
=3
(3)1.2×2.5+0.8×2.5
=2.5(1.2+0.8)
=25
(4)8.9×1.25-0.9×1.25
=1.25(8.9-0.9)
=10
(5)12.5×7.4×0.8
=12.5×0.8×7.4
=74
(6)6.5×9.5+6.5×0.5
=6.5×(9.5+0.5)
=6.5×10
=65
(7)0.35×1.6+0.35×3.4
=0.35*(1.6+3.4)
=0.35*5
=1.75
(8)6.72-3.28-1.72
=6.75-(3.28+1.72)
=6.75-5
=1.75
(9)0.45+6.37+4.55
=0.45+4.55+6.37
=5+6.37
=11.37
(10)28×12.5-12.5×20
=(28-20)*12.5
=8*12.5
=100
(11)23.65-(3.07+3.65)
=23.65-3.65-3.07
=20-3.07
=16.93
(12)(4+0.4×0.25)8×7×1.25
=(4+1)*7*10
=5*7*10
=350
(13)1.65×99+1.65
=1.65*(99+1)
=1.65*100
=165
(14)27.85-(7.85+3.4)
=27.85-7.85+3.4
=20+3.4
=23.4
(15)48×1.25+50×1.25×0.2×8
7.8×9.9+0.78
=7.8*(9.9+0.1)
=7.8*10
=78
(16)4.8×46+4.8×54
=(46+54)*4.8
=100*4.8
=480
(17)673-327-173
=673-(327+173)
=673-500
=173
(18)4.44*2.5
=1.11*(4*2.5)
=1.11*10
=11.1
(19)3.5÷1.4
=(3.5÷0.7)÷(1.4÷0.7)
=5÷2
=2.5
(20)1+2+3+4+5......+99+100
=(1+99)+(2+98)+(3+97)+......+(49+51)+50
=(100÷2-1)*100+50
=4900+50
=4950、