Question

五上小数的简便运算

Answer 1

399.6×9－1998×0.8

= 399.6×9－1998×2×0.4

= 399.6×9－399.6×4

= 399.6×5

=1998

12.9÷0.72+43.5÷3.6

=(12.9×5)÷(0.72×5)+43.5÷3.6

=64.5÷3.6+43.5÷3.6

=(64.5+43.5)÷3.6

=30

49.5×13.5－0.5×49.5+50.5×13

=49.5×(13.5－0.5)+50.5×13

=49.5×13+50.5×13

=(49.5+50.5)×13

=1300

36×2.54+1.8×49.2

=1.8×20×2.54+1.8×49.2

=1.8×(20×2.54)+1.8×49.2

=1.8×(50.8+49.2)

=1.8×100

=180

1.1×1.1×11－1.1×1.1－1.1

=1.1×1.1×(11－1)－1.1

=1.1×11－1.1

=1.1×(11－1)

=11

1992×27.5+1982×72.5

=(1982+10)×27.5+1982×72.5

=1982×(27.5+72.5)+10×27.5

=198200+275

=198475

100×9.5×0.98+9.5×2

=100×0.98×9.5+9.5×2

=9.5×(98+2）

=9.5×100

=950