Question

简便计算方法的数学题

简便方法计算：
1.
2/3*1/4*3 （8/9+4/27）*27 87*3/86
2.
2/9-7/16*2/9 2/5*4*3/4 1/2*1/15+1/3*1/2
4/5*7/9*5/8 5/6*5/9+5/9*1/6 5/7*16*21/5

Answer 1

1.
2/3*1/4*3
=(2/3*3)*1/4
=2*1/4
=1/2
（8/9+4/27）*27
=8/9*27+4/27*27
=24+4
=28
87*3/86
=(86+1)*3/86
=86*3/86+1*3/86
=3+3/86
=3又3/86
2.
2/9-7/16*2/9
=2/9*(1-7/16)
=2/9*9/16
=1/8
2/5*4*3/4
=2/5*(4*3/4)
=2/5*3
=6/5
1/2*1/15+1/3*1/2
=1/2*(1/15+1/3)
=1/2*2/5
=1/5
4/5*7/9*5/8
=(4/5*5/8)*7/9
=1/2*7/9
=7/18
5/6*5/9+5/9*1/6
=5/9*(5/6+1/6)
=5/9*1
=5/9
5/7*16*21/5
=(5/7*21/5)*16
=3*16
=48