[伯問] 請各路英雄幫忙解一下數學...

[lbebel (USC)]

how many positive integers less than 20 are

either a multiple of 2 and odd multiple of 9,

or

the sum of a positive multiple of 2 and 9?

答案是15...

可是為什麼..

--
※ 發信站: 批踢踢實業坊(ptt.cc) 
◆ From: 122.116.13.168