[ohwaitnvm]

He reduced 2040 to 204 by dividing by 2 and 5 because he’s not interested in the factoring so much as just whether 7 is a factor.

[CurtMonash]

Correct.

If I'm checking for any prime other than 2 or 5 -- each of which has it own quick-check anyway via the last digit only -- it's always OK to drop trailing zeros.