LCM of 18, 24 and 32:
–> 18 = 2 x 3 x 3
–> 24 = 2 x 2 x 2 x 3
–> 32 = 2 x 2 x 2 x 2 x 2
LCM = 2 x 2 x 2 x 2 x 2 x 3 x 3 = 288.

The smallest four digit number that is divisible by 288:
288 x 3 = 864
288 x 4 = 1152

Since 288 is divisible by 18, 24 and 32, 1152 is also divisible by all these numbers. Therefore, 1152 is the smallest four digit number divisible by 18, 24 and 32.