Multiply a two digit-number by 101 in one second

You can multiply any two digit-number by 101 in one second or maybe less using this amazing multiplication trick.

Let ab represent the number you would like to multiply by 101.

Then,  ab × 101 = abab 

Examples

64 × 101 = 6464

12 × 101 = 1212

10 × 101 = 1010

99 × 101 = 9999

51 × 101 = 5151

37 × 101 = 3737