(1+19/91*1)+(1+19/91*2)+(1+19/91*3)+……+(1+19/91*13)

问题描述:

(1+19/91*1)+(1+19/91*2)+(1+19/91*3)+……+(1+19/91*13)

(1+19/91*1)+(1+19/91*2)+(1+19/91*3)+……+(1+19/91*13)
=1×13+(19/91)×(1+2+3+……+13)
=13+19/91×91
=13+19
=32