- if i < 0, its num = 0 (since we are doing sum, blindly setting 0 is okay) - Note: `sb.insert(0, x)` is much slower than doing a final `sb.reverse()` #### If manually convertin to int[] 1. when ...

- let num1 = multipier, num2 = base. mutiply and save into int[m + n]. - Loop over num1, each row num1[x] * num2, save to correct index (i + j + 1) - Note: skip leading '0' during output, but do not ...