Calvin and Susan play a Number-Game #1
For example : If Calvin's number begins \(2112\), Susan's number would begin \(111122122111\).
After Susan finishes writing her number, she notices that the left-most 2500 digits in her number is exactly same as that of the left-most 2500 digits of Calvin's number. Then find the sum of the seven digits in the positions 2006 to 2012, both inclusive.
Also try it's sister problem, a difficult version: Calvin and Susan play a Number-Game #2