Mini-Sudoku
How many ways are there of completing the mini-sudoku?
Age
11 to 14
Challenge level
Problem
Image
A mini-sudoku is a 4 by 4 grid, where each row, column and 2 by 2 outlined block contains the digits 1, 2, 3 and 4 once and once only.
How many different ways are there of completing the mini-sudoku shown?
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.
Student Solutions
The top 2 by 2 outlined block must contain a 3 and a 4, and this can be done in two ways. For each choice there is only one way to complete the entire mini-sudoku.