Count by 10s

My four-year-old, Gomez, told my seven-year-old, Mars, that he was smarter.
Mars: No you're not.
Gomez: Yes, I am.
Mars: If you're so smart, count ten times by ten.
Gomez: Ten, ten, ten, ten, ten, ten, ten, ten, ten, ten

I'd say he won that round.