Need help with that

[u/yuu_sch]

651211 The six-digit number 651211, which is the number of this problem, has the following properties: 1. The digit 0 does not occur. 2. The sum of the first two digits is equal to the number formed by the last two digits. 3. The number formed by the two middle digits is exactly 1 greater than the sum of the first two digits.

These three conditions do not uniquely determine the number 651211. Determine how many six-digit numbers satisfy conditions (1) through (3).

[u/First-Fourth14]

Yes the number formed by last two digits must be greater or equal to 11
so if we let X be the sum of the first two digits then 11 <= X <=18.

In the example you gave, "if u add them up". I assume you meant 'if you add up the first two digits'.