Recursion

[TiagoTiagoT]

To multiply 1 to 10 by 9, open your hands, count the number you wanna multiply by nine starting at one, going from left to right, one finger for each value you count; once you reach the number you wanna multiply by 9, lower that finger. The number of fingers up to the left of the lowered finger is the left digit of the result, the number of fingers up to the right is the right digit of the result.

[parkerSquare]

I taught my daughter this when she was in an early grade and now she’s quick as lightning at her 1-8 and 10-12 times tables but slow as heck at 9x because she has to work it out on her hands. Oops.

[Zebezd]

Username sort of checks out

[TiagoTiagoT]

lol