







What is the sum of the numbers missing from this Sudoku puzzle?
1. Don’t solve this Sudoku puzzle yet.
2. Add up the numbers you can see in the Sudoku grid.
3. Calculate the sum of the numbers that would be in the completed puzzle.
4. Calculate the sum of the numbers that are missing.
5. Finally complete the puzzle to see if your answers to 3 and 4 were correct.
Topics: Starter  Arithmetic  Multiple Intelligences  Puzzles
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Previous Day  This starter is for 22 April  Next Day
The sum of the missing numbers is 70
You did not need to complete the sudoku puzzle to find this answer. The completed puzzle could look like this (though there might be other solutions).








Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.
Teacher, do your students have access to computers such as tablets, iPads or Laptops? This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments: Transum.org/go/?Start=April22 However it would be better to assign one of the student interactive activities below. 

Here is the URL which will take them to an interactive Sudoku activity.
Here is the URL which will take them to similar number puzzles called Suko and Sujiko.