# Difference square logic (5x5)

Rules :

• Arrange numbers 1 to 25 to the squares, and each number only occurs once.
• Green squares are the difference from its left square and its right square.
• Green squares are also the difference from square above it and square below it.
• Solve them without computer.
• You can post answer to each question separately.

Example:

Questions

Questions 1

Questions 2

Questions 3

Questions 4

Questions 5

• This is an interesting idea, and seems great, but the puzzles seem a bit too easy... I would recommend some kind of twist Commented May 30, 2017 at 8:11
• @Wen1now : Thankyou, I'll try to make bigger and harder kind of this. Commented May 30, 2017 at 8:20
• Not necessarily bigger, just more interesting... like more operations (e.g the green squares are either $+ - \div \times$) which would mean that the solver has to actually deduce which one is being used Commented May 30, 2017 at 8:32
• Assuming you can keep the numbers below 26, you could also use letters. Maybe encode a message? Commented May 30, 2017 at 13:41

I'll post these as I go.

1:

Note that the bottom left 23 must be 1-24 or 2-25. However all combination of 2-25 and one of 1-24 don't work so we must have:

After checking all possibilities, the 12 can only be satisfied with 25-13, from which we deduce 25 must go top right. Then number chase and the finished puzzle is:

2:

Ooh, this question is actually not 100% straightforward! Okay, firstly look at the bottom left 23. It is either a 1-24 or 2-25, with one orientation of each being knocked out. Doing the two alive ways, and number chasing around we have:
Look at the right grid. 25 cannot go next to either the 14 nor the 6, so we can kill it. Thus we only need to do the left grid. But 15 must go top left, so we number chase around and finish:

3:

Okay, the top left square is either 1,2,3,23,24 or 25. Only 24 survives after a quick cull:

Then 23 must go bottom left. Number chase around to finish:

4:

Same thing, the bottom left 23 must be 2-25. We eliminate one of them, number chase to get the 'outer square':

3 must go top right:

5:

Observe that the bottom left 18 must be done with a 7-25 since smaller numbers have already been taken. 25 cannot go bottom as then 8 must go bottom middle. Number chase around to get these numbers:

Then to finish note that the 11 must be satisfied by 21-10 so since 10 can't go left, we must have ten on the left. Number chase to finish: