简算怎么做,谢谢
1个回答
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27×99
=27×100-27×1
=2700-30+3
=2673
28×250
=250×4×7
=1000×7
=7000
98×303
=100×303-2×303
=30300-606
=29694
49+49×49
=49×1+49×49
=49×(1+49)
=(50-1)×50
=2500-50
=2450
=27×100-27×1
=2700-30+3
=2673
28×250
=250×4×7
=1000×7
=7000
98×303
=100×303-2×303
=30300-606
=29694
49+49×49
=49×1+49×49
=49×(1+49)
=(50-1)×50
=2500-50
=2450
追答
55×25+25×4.5
=25×(55+5-0.5)
=25×60-12.5
=1500-13+0.5
=1487.5
123×67-23×67
=(123-23)×67
=100×67
=6700
39×101-39
=39×101-39×1
=39×(101-1)
=39×100
=3900
99×64+64
=99×64+64×1
=64×(99+1)
=64×100
=6400
76×23+24×23
=23×(76+24)
=23×100
=2300
12+19×12
=12×1+19×12
=12×(1+19)
=12×20
=240
21+254+79+46
=(21+79)+(254+46)
=100+300
=400
25×16×5
=(25×4)×(4×5)
=100×20
=2000
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