Question 539852
use the 3 trick when counting with 5s starting at 15 1+5=6 so its divisible by 3
15,30,45,60,75,90,105,120,135,150,165,180,195
above are the possibilities for 3 n 5 but some are divisible by 4 and 7 so go through and knock those out
15,30,45,{{{cross(60)}}},75,90,{{{cross(105)}}},{{{cross(120)}}},135,150,165,{{{cross(180)}}},195