小学六年级数学用简便方法计算

7*8/15-7*12/35+7*16/63-20/99*7
=7*8/15-12/5+16/9-140/99
=56/15-36/15+176/99-140/99
=20/15+36/99
=4/3+4/11
=44/33+12/33
=56/33

=56/15-84/35+112/63-140/99
=56/15-12/5+16/9-140/99
=(56/15-36/15)+(176/99-140/99)
=20/15+36/99
=4/3+4/11
=44/33+12/33
=56/33

=7*(8/15-12/35+16/63-20/99)
=7*(4/21+4/567)
=7*112/567
=112/81

=7*(8/15-12/35+16/63-20/99)
=7*(4/21+4/567)
=7*112/567
=112/81
望采纳

7*(8/15-12/35+16/63-20/99
=7*4(2/15-3/35+4/63-5/99)
=28*(1/3-1/5+1/5-2/7+2/7-2/9-(2/9-2/11)-1/99)
=28*(1/3+2/11-1/99)
=28*50/99

最好用计算器！