Find the common factors of
6,15,18
Factors of 6=1,2,3,6
Factors of 15=1,3,5,15
Factors of 18=1,3,6,9,18
Hence, common factors of 6,15,18 are 1,3.
Find the least number which when divided by 6,15,18 leave the remainder 5 in each case.