计算除数是两位数的除法时,只要试商必然一次成功. .
:16=15÷ == %= (填小数)
÷ = :16=5÷ = %=0.25.
0.8=12÷ = :10= %
÷ =8﹕ = ﹕15==.
%=15÷ ==0.3: =0.75= 折= (填成数).