Answer: We have two solutions:
1000 - 998 = 2
1001 - 999 = 2
Step-by-step explanation:
So we have the problem:
****-*** = 2
where each star is a different digit, so in this case, we have a 4 digit number minus a 3 digit number, and the difference is 2.
we know that if we have a number like 99*, we can add a number between 1 and 9 and we will have a 4-digit as a result:
So we could write this as:
1000 - 998 = 2
now, if we add one to each number, the difference will be the same, and the number of digits in each number will remain equal:
1000 - 998 + 1 - 1 = 2
(1000 + 1) - (998 + 1) = 2
1001 - 999 = 2
now, there is a trivial case where we can find other solutions where the digits can be zero, like:
0004 - 0002 = 2
But this is trivial, so we can ignore this case.
Then we have two different solutions.
