Answer
$180$
Work Step by Step
The multiples of $18$ are:
{$18,36,54,72,90,108,126,144,162,180,198.......$}
The multiples of $20$ are:
{$20,40,60,80,100,120,140,160,180,200....$}
Amongst the two sets, it is seen that the least common multiple is $180$.
