It's quick maths

Any form of doing math that takes an extra step and still gets the right answer, isn't weird, it's valid.
I for one would say 6=2×3. So, two threes.
Then 7+3=10 +3=13

I have ADHD so this is how I math sometimes

This and also breaking a three digit number into two or more pieces, and adding those up.
Ex: 457+512 becomes 450+510 and 7+2.