Here’s one short-cut.

How to multiply double-digit numbers by 11.

Example: MULTIPLY 45 x 11.

Step 1: The answer will start with 4 and end with 5. So it’s 4__5

Step 2: Find out what’s in the blank by adding 4+5=9

Step 3: The answer is 495

Another example: MULTIPLY 63 X 11

Step 1: The answer is 6_3.

Step 2: The blank is 6+3=9

Step 3: The answer is 693