简便计算:20-2/3-2/15-2/35-2/63-2/99的列式和答案
问题描述:
简便计算:20-2/3-2/15-2/35-2/63-2/99的列式和答案
答
=20-(2/1*3+2/3*5+2/5*7+2/7*9+2/9*11)
=20-(1-1/3+1/3-1/5+1/5-1/7+17-1/9+1/9-1/11)
=20-(1-1/11)
=19又1/11