简算 51.5-8.56-1.44 21*102-21*2 25*125*32 7.91*3+3*2.09 45*98+45*2

51.5-8.56-1.44 21*102-21*2
=51.5-(8.56+1.44) =21*(102-2)
=51.5-10 =21*100
=41.5 =2100
7.91*3+3*2.09 45*98+45*2
=3*(7.91+2.09) =45*(98+2)
=3*10 =45*100
=30 =4500
25*125*32
=25*4*（125*8）
=100*1000
=100000

51.5-8.56-1.44
=51.5-（8.56+1.44）
=51.5-10
=41.5
21*102-21*2
=21*（102-2）
=21*100
=2100
25*125*32
=25*4*（125*8）
=100*1000
=100000
7.91*3+3*2.09
=（7.91+2.09）*3
=10*3
=30
45*98+45*2
=45*（98+2）
=45*100
=4500