Answer:
[tex]6,\ 12,\ 18[/tex]
Step-by-step explanation:
Multiple of a Number: Multiple of a number is the multiplication of that number and an integer.
First Multiple: First multiple of a number is number itself.
Multiples of 6:
[tex]6\times 1=6\\\\6\times 2=12\\\\6\times 3=18\\\\6\times 4=24\\\\but\ 24>20\\\\Hence\ multiples\ of\ 6\ less\ than\ 20=6,\ 12,\ 18[/tex]