If you don't know up to 9x9, then doing basic algebraic problems become vary cumbersome. Factoring and simplification becomes a chore and one can't get into a g

If you don't know up to 9x9, then doing basic algebraic problems become vary cumbersome. Factoring and simplification becomes a chore and one can't get into a good flow if you are typing in 2x5 into a calculator. On the other hand, I can't imagine anywhere that would expect one to know 11x15 off the top of ones head.