从1至35的自然数中选5个数,和值等于95的有多少种?答:数字不重复使用,不计顺序,共5772种:1,2,23,34,35,1,2,24,33,35,1,2,25,32,35,………16,17,19,21,22,16,18,19,20,22,17,18,19,20,21,
从1至35的自然数中选5个数,和值等于89的有多少种?答:数字不重复使用,不计顺序,共5907组:1,2,17,34,35,1,2,18,33,35,1,2,19,32,35,………15,16,17,20,21,15,16,18,19,21,15,17,18,19,20,