Learn how to double any two or three digit numbers mentally. Find app on Google Play https://play.google.com/store/apps/details?id=com.novellectual.mathchallenge

1. Fast Math Tricks
Vedic Math

2. This tutorial will teach you a technique
to double any two or three digit
numbers mentally.

3. Consider the following example.

4. Double the higher digits of the number (the
10s and 100s digits).

5. If the lower digit is larger than 4, add one to
the result.

6. Double the lower digit (here 7x2) and ignore
the 10s part (here, take only 4). Append to
the result to produce the answer.

7. Get the app for more tutorials and practice