You can easily multiply two numbers between 11 and 19 in your head using this method.
For example, you want to find what 14 x 15 equals...
Take the number 14 and the second digit of the second number, i.e. 5 and add them together.
This gives 19.
Now stick a zero at the end of that, so it becomes 190.
Remember that number.
Now take the second digit from each number, i.e. 4 and 5, and multiply them together to give 20.
Add this number to the number you calculated in the previous step, i.e. 20+190, and you get 210