下面各题怎样算简便就怎样算. ①1.8×1/4+2.2×25% ②99×61.25+61.25 ③9/20÷〔1/2×(2/5+4/5)〕 ④45+99×99+54.
问题描述:
下面各题怎样算简便就怎样算.
①1.8×
+2.2×25%1 4
②99×61.25+61.25
③
÷〔9 20
×(1 2
+2 5
)〕4 5
④45+99×99+54.
答
(1)1.8×
+2.2×25%,1 4
=(1.8+2.2)×25%,
=4×25%,
=1;
(2)99×61.25+61.25,
=(99+1)×61.25,
=100×61.25,
=6125;
(3)
÷〔9 20
×(1 2
+2 5
)〕,4 5
=
÷〔9 20
×1 2
],6 5
=
÷9 20
,3 5
=
;3 4
(4)45+99×99+54,
=(45+54)+99×99,
=99+99×99,
=(99+1)×99,
=100×99,
=9900.