Too big to fit is the simplest Kakurasu technique: a square worth more than what’s left of its line’s target can’t be shaded, so cross it out. A row needing 5 can’t use squares 6 or 7. A row that needs 9 and already has square 6 shaded only has 3 left, so squares 4, 5 and 7 are out.
This is the second of the Kakurasu techniques.
The rule
For each line, work out what’s left: the target minus the squares already shaded. Every open square worth more than that is out.
It’s at its most useful partway through a puzzle, once a line has a square or two shaded and only a little is left.
In a real puzzle
On the 7×7 used on every technique page, two rows have small targets: row 2 needs 4 and row 7 needs 2.
Applied to every row and column at the start of a puzzle, this is the opening sweep: a quick pass that crosses out every square too big for its row or its column.
Its mirror
Too big to fit only ever crosses squares out. Its partner, counting the empty squares, works the same way from the other side: a square worth more than the empty squares can add up to must be shaded. Between them they cover both ends of every line: small targets cross squares out, big targets shade them in.
Watch out for
- Using the full target instead of what’s left. The rule is only as good as your subtraction. See losing track of what’s already shaded.
- Reading the wrong numbers in a column. Down a column, compare against row numbers, not column numbers.