There are similar mental math tricks for other numbers too.
For multiplying by 8: Multiply the number by 10 then subtract twice the original. Example: 25 x 8 is 250 minus 50 equals 200. Or just double it three times.
For multiplying by 15: Multiply by 10 then add half of that result. Example: 24 x 15 is 240 plus 120 equals 360.
For multiplying by 55: Multiply by 11 first using the digit trick from the video, then multiply the result by 5. Example: 23 x 11 is 253, then x 5 is 1265.
These make quick mental math easy.