BIG Multiplication by subtracting Easy Math Trick

This multiplication trick is really pretty obvious when you think about it.
Do you know it?

Here is THE mental multiplication lesson playlist - progressing you through your mental multiplication.
https://www.youtube.com/playli....st?list=PLjbxBzUM6SL

Here is that link how to multiply questions like 3 x 54 instantly
https://youtu.be/yZULgerBRms


To donate to the tecmath channel:https://paypal.me/tecmath

To support tecmath on Patreon: https://www.patreon.com/tecmath

To buy tecmath mechandise: https://teespring.com/stores/tecmath-store