问题
解答题
简便运算: (1)2.9+29.9+299.9+2999.9 (2)(
|
答案
(1)2.9+29.9+299.9+2999.9,
=3-0.1+30-0.1+300-0.1+3000-0.1,
=3+30+300+3000-(0.1+0.1+0.1+0.1),
=3333-0.4,
=3332.6;
(2)(
+5 9
)÷7 18
×5,1 18
=(
+5 9
)×18×5,7 18
=
×18×5+5 9
×18×5,7 18
=50-35,
=15.