>>14337952Start working out how to change equations into ones that you can quickly solve.
Like for example, anything x5 is really easy, because it's just half of whatever that number is x10, and once you understand that you can easily do x15 just by adding them together, and x25 by doubling your x10 result and adding the x5, and so on and so on.
>412 * 15 = 4120 + 2060 = 6180You can also use similar techniques for any arbitrary ending digit, not just 5, by just doing the easy x10 numbers and adding whatever the final digit multiplies to
>173 * 103 = 17300 + 519 (x3 original number, broken down as 170 * 3 + 9) = 17819The same sort of techniques work pretty well for division as well
