Rich chooses a 4-digit positive integer. He erases one of the digits of this integer. The remaining digits, in their original 4-digit integer, the result is 6031. What is the sum of the digits of the

Question

Can the answers have good proof, and a good understanding of HOW you got the answer, and the steps. Please and thank you.

Question Cont'd: original 4-digit number?

Answer 1

If he erases one of the digits in a 4-digit number, then only 3 remain, not four.

If he erased the first digit, then it must have been 1-9, so the total is in the range 11 - 19

otherwise the digit could have been 0-9 in which case the total is in the range 10-19