How to solve Shikaku
For each number, list the rectangles that fit. Place the ones with a single fit, give each cell to the only number that reaches it, and use the cells every option shares.
How it works
Shikaku gives you a grid with numbers in some cells. Divide the whole grid into rectangles. Each rectangle holds exactly one number, and that number is its area.
The numbers always add up to the size of the grid, so every cell ends up in exactly one rectangle. There are no gaps and no overlaps.
Solve it by listing options: the rectangles of the right area that stay on the grid and hold no other number. Then cut the lists down until each number has one left.
Where to look first
Big numbers in tight spots and small numbers boxed in by other numbers have the fewest options. Corners are good: a cell in a corner can only be reached from two directions.
After each rectangle, look at its neighbours. They just lost cells, and one of them may be down to a single fit.
Worth memorizing
List the options.
Right area, on the grid, no other number inside.
One fit: draw it.
Then check the neighbours.
A cell only one number reaches is that number’s.
Practice
0 of 4 rightHow many options does the ringed 6 have at the start?
How many options does the ringed 2 have at the start?
With the bottom row drawn, how many options does the ringed 3 have?
Which cells do all the options of the ringed 6 share?