Multiplying a 2-digit number by 55 (method 2)

1. Select a 2-digit number.
2. Multiply it by 5.
3. Add the digits from left to right.

   Example:

1. The 2-digit number chosen to multiply by 55 is 42.
2. Multiply by 5: 5 x 42 = 200 + 10 = 210
3. The last digit is 0:   _ _ _ 0
   Add right to left: 0 + 1 = 1   _ _ 1 _
   1 + 2 = 3:   _ 3 _ _
   The first digit is the same:   2 _ _ _
4. So 55 x 42 = 2310.

   See the pattern?

1. If the 2-digit number chosen to multiply by 55 is 86:
2. Multiply by 5: 5 x 86 = 400 + 30 = 430
3. The last digit is 0:   _ _ _ 0
   Add right to left: 0 + 3 = 3   _ _ 3 _
   3 + 4 = 7:   _ 7 _ _
   The first digit is the same:   4 _ _ _
4. So 55 x 86 = 4370.