Originally posted by: JustRandomGirl
Shreya for the sudoku can give an example by what you mean by adding up numbers to the dashed boxes? Can give one example for multiple boxes for the dashes?
Yes. So for example, let's take the top left 3 x 3 box from this puzzle. In a sudoku each 3 x 3 box, row, and column can only have 1 through 9 once. Along with that though, in the top row, the 3 numbers have to add up to 10. Then 2 numbers have to add up to 15, 2 numbers to 7, and 2 numbers to 13. So now when you're solving it, you can't just put numbers anywhere. You also need to put them in a way that they add up to that sum.
So like for 15, the 2 options are 6 + 9 or 7 + 8. For 7, you have 1 + 6, 2 + 5, 3 + 4. For 13, you have 5 + 8, 6 + 7, 4 + 9.
Here's a trick - first put in the numbers where it's a single box. Like 1 box saying 3 is the sum. Obviously only 3 can add up to 3. Then start going through the additions where you have numbers already. Like if the 15 here had 7 already you would know the other number has to be 8. Then try to fill the others in.

718