Answer:
121
Step-by-step explanation:
Hello!
A quick rule for multiplying two digit numbers by 11, is to take the first digit, and the second digit, and place the sum of those two in the middle.
For example:
- 22 * 11
- I create a space betweem the two digits: 2 _ 2
- Now, I take the sum of 2 and 2: 4
- And I place it in the space: 242
This works for any two digits number. I recommend memorizing the squares of the first 20 numbers:
- 1² = 1
- 2² = 4
- 3² = 9
- 4² = 16
- 5² = 25
- 6² = 36
- 7² = 49
- 8² = 64
- 9² = 81
- 10² = 100
- 11² = 121
- 12² = 144
- 13² = 169
- 14² = 196
- 15² = 225
- 16² = 256
- 17² = 289
- 18² = 324
- 19² = 361
- 20² = 400
