Labs · prototype
Pleat
Fold the 4×4 grid once horizontally (left or right) and once vertically (top or bottom) to get a 2×2 grid where each cell is a stack of four numbers. The four stack-sums must land in the positions shown in the target. Which fold direction you pick decides where each sum ends up — match the target.
The sheet
2
5
1
8
3
7
4
6
9
1
5
2
4
8
3
7
Horizontal fold
Vertical fold
Your stacks
·
·
·
·
Target
17
20
17
21