Here is another way of thinking about the trick...
For 54 x 11, set out a column addition with 54 as the first number to add.
Write 54 again, below the first 54, but this time line up the 4 in the ones column of the second 54 with the 5 in the tens column of the first 54.
Add them together:
What digit is missing from the ones column of the second number in the sum?
What do you know about numbers that end in that digit?