问题
解答题
用简便方法计算(要写出简算过程) ①475-198 ②0.7+3.9+4.3+6.1 ③(
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答案
①475-198,
=475-(200-2),
=475-200+2,
=275+2,
=277;
②0.7+3.9+4.3+6.1,
=(0.7+4.3)+(3.9+6.1),
=5+10,
=15;
③(
+1 3
)×15,2 5
=
×15+1 3
×15,2 5
=5+6,
=11.