Sum to Twenty-One Puzzle
Today I’m sharing the Sum to Twenty-One Puzzle with you. Previously, I have shared similar puzzles called Sum to Twenty and Sum to Thirty. These puzzles are the creation of Marcy Cook.

They were shared in THINK ABOUT IT! Mathematics Problems of the Day which was published by Creative Publications in 1982.
The book is out of print and very hard to find copies of online.
In the Sum to Twenty-One Puzzle, students are given a 4 x 4 grid that already has six numbers filled in. Their task is to place the numbers 0-9 in the grid so that each row, diagonal, and column sums to 21.
If you like this magic square style puzzle, I also recommend checking out the Big Magic Puzzle.
Interested in even more puzzles? Check out my puzzles page!
Free Download of Sum to Twenty-One Puzzle
I have created a printable PDF version of this puzzle. If you would like to edit it, I have uploaded the editable Publisher version. Since we’re currently in the middle of a pandemic, I have also created some digital versions which I will share below.
Click here to Download
Sum to Twenty-One Puzzle (PDF)
4927 downloads – 173.99 KB
Puzzle Solutions
Puzzle solutions are available on a password-protected solution page. I do not openly post the puzzle answer keys because one of my goals as a resource creator is to craft learning experiences for students that are non-google-able. I want teachers to be able to use these puzzles in their classrooms without the solutions being found easily on the Internet.
Please email me at sarah@mathequalslove.net for the password to the answer key database featuring all of my printable puzzles and math worksheets. I frequently have students emailing me for the answer key, so please specify in your email what school you teach at and what subjects you teach. If you do not provide these details, I will not be able to send you the password.
Not a teacher? Go ahead and send me an email as well. Just let me know what you are using the puzzles for. I am continually in awe of how many people are using these puzzles with scouting groups, with senior adults battling dementia, or as fun activities in their workplace. Just give me enough details so I know you are not a student looking for answers to the puzzle that was assigned as their homework!