递等式,怎样简便怎么算 0.98*302=? 25*4.4*0.7=? 5.8*5.8+5.8*0.5+5.8=? (0.25*12.5)*(4*0.8)=?105*105=? 32*1.25=?2.3+1.7*5.5=?急!
问题描述：
递等式,怎样简便怎么算 0.98*302=? 25*4.4*0.7=? 5.8*5.8+5.8*0.5+5.8=? (0.25*12.5)*(4*0.8)=?
105*105=? 32*1.25=?2.3+1.7*5.5=?急!
答
0.98*302
=0.98*(300+2)
=0.98*300+0.98*2
=294+1.76
=295.76
25*4.4*0.7
=(25*4)*(1.1*0.7)
=100*0.77
=77
5.8*5.8+5.8*0.5+5.8
=(5.8+0.5+1)*5.8
=7.3*5.8
=42.34
(0.25*12.5)*(4*0.8)
=(0.25*4)*(12.5*0.8)
=1*10
=10