TIPS for calculating math faster(2)

how to calculate 23 x 27 less than 2 seconds?
here it is:
23 x 27 = ...
i) add 1 to 2 = 3, then multiply by 2 = 3 x 2 = 6
ii) multiply 3 by 7 = 3 x 7 = 21
the answer is 621.

try for 36 x 34 = ...
i) add 1 to 3 = 4, then multiply by 3 = 4 x 3 = 12
ii) 6 x 4 = 24.
the answer is 1224.

easy right?
now, do exercises with other numbers! try until u can do it <>
can you find the rules that applies for these multiplications?
all the best for you!!!