Question

Find the least number of five digits divisible by each of the numbers 12,18,and 30

Answer 1

1, 2,3,6,and³/2 are divisible by 12, 18, and 30

Answer 2

L.C.M (12,18,30)
12 = 2^2 * 3
18 = 2 * 3^2
30 = 2*3*5
L.C.M = 4*9*5 = 180
Least 5 digit number = 10000
10000/18 leaves a remainder 100.
Hence 10000+(180-100) = 10080 is the least  number which is divisible by each of 12,18,30 
Highest 5 digit number = 99999
99999/180 = Quotient 555
Least 5 digit number = 10000
10000/180 = Quotient 55
Number of 5 digit numbers divisible by each are: 555-55 = 500

Hence LEAST 5 digit number divisible by 12.18,30 is 10080 (and number of 5 digit numbers divisible are 500)