what is the smallest number of pencils that are needed to put into jars holding 3,6 and 9 leaving no remainder.

If those are the numbers that you MUST put into each jar, then

3 + 6 + 9 = ___

However, who says that you have to put any pencils in jars. They only tell you how many the jars hold.

This is a poorly worded question. Not your fault.