Sorry: for those who don't see it:

23 x 11: sprtead the 2 and 3 apart. Add them. The sum is 5. Put that in the middle. Therefore, 23 x 11 = 253. Note that when the number to be multiplied by 11 will add to over 10, there will be a carry over TO THE LEFT. So, 49 x 11 will equal (from right to left) 9. Middle number will be 3 (from the addition of 4 and 9. The 1 that's left will move left and be added to the 4.) Our answer is then 539.

When the number 135 is multiplied by 11, forget about the 3, it will be removed. That will be handled by the math.

1    3    5

Keep the 1. Add 1 and 3. Put the 4 to the right of the 1. Add the 3 and the 5. Put the 8 to the right of the 3. NOW, forget the 3. Keep the 5. Our answer is 1485. That is 135 x 11.