Question

用递等式计算（怎样简便就怎样计算）． 0.25×5×1.6	4.28+4.72×2.5
3.14×5.5+0.314×45	19.72×101-19.72
3.7×4.85+16.07	（0.718+0.718+0.718+0.718）×0.25．

Answer 1

（1）0.25×5×1.6
=0.25×5×4×0.4
=（0.25×4）×（5×0.4）
=1×2
=2；

（2）4.28+4.72×2.5
=4.28+1.18×4×2.5
=4.28+1.18×（4×2.5）
=4.28+1.18×10
=4.28+11.8
=16.08；

（3）3.14×5.5+0.314×45
=3.14×5.5+3.14×4.5
=3.14×（5.5+4.5）
=3.14×10
=31.4；

（4）19.72×101-19.72
=19.72×（101-1）
=19.72×100
=1972；

（5）3.7×4.85+16.07
=17.945+16.07
=34.015；

（6）（0.718+0.718+0.718+0.718）×0.25
=（0.718×4）×0.25
=0.718×（4×0.25）
=0.718×1
=0.718．