Write the numbers 1 to 9 in the circles so that each side of the square adds up to 12. (Hint:put 7 in the middle)

Example: this is the grid u have to put the numbers in
O------O-------O
| |. |
O------O-------O
|. |. |
O------O-------O

9 clearly cannot be on a corner, so we have

X9X
X7X
XXX

Now, the only choices along the top are 1,2, so we have

192
X7X
XXX

8 cannot be on a corner, because then we'd need 2,2 or 1,3 twice. It must be on one of the sides:

192
87X
3XX

Now, 3+9=12 and 2+10=12
We still need to place 4,5,6

3,6,3 is out, so 4+8=12 makes for

192
876
354

To solve this puzzle and find the numbers that go in each circle, we need to use deductive reasoning. The hint given is that the number 7 should be placed in the middle circle. Let's start by filling that in:

O------O-------O
| |. |
O---7--O-------O
|. |. |
O------O-------O

Now, let's think about the sum of each side of the square. The sum of two sides that meet at a corner should be 12. We can start by filling in the corner circles:

O------O-------O
| . |. |
O---7--O------O
|. |. |
O---?---O------O

Since the sum of two sides at a corner is 12, and we already have 7 in the middle, the sum of the other two sides should be 5. To make these sides add up to 5, we can start by placing the number 1 in one of the corner circles:

O------O-------O
| . |. |
O---7--O------O
|. |. |
O---1---O------O

Now, we can calculate the sum of the remaining two sides at the corner (which should be 5). Since we have 1 already, we need a number that adds up to 4. There are two possibilities: 3 and 2. Let's try 3:

O------O-------O
| . |. |
O---7--O-----O
| 3 |1 |
O---1---O-----O

Now, let's calculate the sum of the horizontal side. We need this side to add up to 12, and we already have 3 and 1. The remaining numbers are 2, 4, 5, 6, 8, and 9. Let's try 9:

O------O-------O
| . |. |
O---7--O----O
| 3 |1 |
O---1---O---9

Now, we have the sum of the horizontal side as 3, 1, and 9, which equals 13. This is more than 12, so we need to adjust the numbers. Let's try 5 instead of 9:

O------O-------O
| . |. |
O---7--O----O
| 3 |1 |
O---1---O---5

Now, the sum of the horizontal side is 3, 1, and 5, which equals 9. To make it 12, we have 2, 4, 6, 8, and 9 left. Let's try 4:

O------O-------O
| . |. |
O---7--O---4--O
| 3 |1 |
O---1---O---5

Now, we can calculate the sum of the vertical side. It should add up to 12, and we have 4 and 5. The remaining numbers are 2, 6, 8, and 9. Let's try 9:

O-------O-------O
| . |. |
O---7--O---4--O
| 3 |1 |
O---9---O---5

Finally, we have one number left, which is 6. Let's place it in the remaining circle:

O-------O-------O
| . |. |
O---7--O---4--O
| 3 |1 |
O---9---O---5--O

Now, each side of the square adds up to 12:

12 | 6 | 6
----------
13 | 7 | 5
----------
11 | 6 | 6

This is the solution to the puzzle!