Question

54.9X0.38的简便运算

Answer 1

54.9X0.38

=55X0.38-0.1X0.38

=55X0.4-55X0.02-0.038

=22-1.1-0.038

=22-1.138

=20.862

扩展资料

乘法：分配律=ac+ab=a(b+c)

结合律=abc=a(bc)

交换律=ab=ac

积不变性质=ab=(a÷c)×(bc)(c≠0)

加法：结合律=a+b+c=a+(b+c)

交换律=a+b=b+a

除法：a÷b÷c=a÷（b×c）(b≠0,c≠0)

商不变性质=a÷b=(a×d)÷(b×d)(b≠0,d≠0)=(a÷d)÷(b÷d)(b≠0,d≠0)

减法：a-b-c=a-(b+c)

Answer 2

54.9×0.38
=（55-0.1）×（0.4-0.02）
=55×0.4-55×0.02-0.1×0.4+0.1×0.02
=22-1.1-0.04+0.002
=20.862