带分数计算1又1/12 + 2又1/20 + 3又30/1 + 4又1/42 （简便计算）,
问题描述：
带分数计算1又1/12 + 2又1/20 + 3又30/1 + 4又1/42 （简便计算）,
答
1+ 1/12 + 2+ 1/20 + 3+ 1/30 + 4+ 1/42
= 1 + 2 + 3 + 4 + (4-3)/12 + (5-4)/20 + (6-5)/30 + (7-6)/42
= 10 + 4/12 - 3/12 + 5/20 - 4/20 + 6/30 - 5/30 + 7/42 - 6/42
= 10 + 1/3 - 1/4 + 1/4 - 1/5 + 1/5 - 1/6 + 1/6 - 1/7
= 10 + 1/3 - 1/7
= 10 + 7/21 - 3/21
= 10+ 4/21