问题
解答题
神机妙算细又巧! ①
③4×0.8×2.5×12.5④7.8-2.3-2.7 ⑤(
|
答案
①
×7 11
+8 9
÷7 11
,9 10
=
×7 11
+8 9
×7 11
,10 9
=
×(7 11
+8 9
),10 9
=
×2,7 11
=
;14 11
②1375+450÷18×25,
=1375+625,
=2000;
③4×0.8×2.5×12.5,
=4×2.5×(12.5×0.8),
=10×10,
=100;
④7.8-2.3-2.7,
=7.8-(2.3+2.7),
=7.8-5,
=2.8;
⑤(
+7 9
-4 21
)×6.3,3 7
=
×6.3+7 9
×6.3-4 21
×6.3,3 7
=4.9+1.2-2.7,
=3.4;
⑥0.9×(99+0.9),
=0.9×(100-1+0.9),
=0.9×(100-0.1),
=0.9×100-0.1×0.9,
=90-0.09,
=89.91.