Now the first video is almost useful.
He is teaching you to add from left to right, instead of from right to left.
This is useful for doing simple math in your head.
But he is skipping a key step of mental math.
You have to restate the problem after each math step.
Say 24 plus 17.
So you add the 10 to the 24.
The new problem is 34 plus 7.
Then add that.
By repeating this method, you can add large numbers safely.
But you have to put the new problem into your memory by stating it.
“Say 24 plus 17. So you add the 10 to the 24.
The new problem is 34 plus 7. Then add that.”
That’s how I do it without paper. I didn’t realize it was an actual “thing” / method.