Multiplication by 11 is easy! To multiply by a 2-digit number add the two digits and place the sum in between!
31 x 11 = 341
57 x 11 = 627 <-- you need to carry the 1!
What about a 3-digit number? Can you figure out what's going on here?
117 x 11 = 1287
532 x 11 = 5852
267 x 11 = 2937
