Door 24 - Math Offers 600+ Arithmetic Challenges for Grade 3-8

One card game variant that I like to play is the 24 Game. Using four randomly-dealt cards, players need to manipulate the numbers on the cards using any combination of the basic arithmetic operations to make the number 24. For example, when the following cards are dealt: 4, 5, 7, and 8; any of the following solutions is valid:

4 + 5 + 7 + 8 = 24
(5 + 8 - 7) * 4 = 24
(5 + 7) * 8 / 4 = 24
(8 + 4) * (7 - 5) = 24

My app pick for today is a brand new game published by Curriculum Associates as a part of their i-Ready blended learning online program. Called Door 24 - Math, the app uses the principles of the 24 Game in its core gameplay.

Door 24 requires players to find a combination of operands and operators that would yield 24.

Find All Combinations that Yield 24

The premise of this game is for the players to fix the circuits inside Victor the Robot. Something went wrong in Victor’s head after he entered the Door 24, so he locked the door to prevent others from encountering the same problem.

To fix the circuits inside Victor’s head, players need to connect the numbered electrodes to yield the number 24. The numbers in these electrodes and the operators that connect them are generated randomly. For example, the game may show two electrodes: 6 and 30, and a minus operator to connect the two placeholders.

The game is organised into levels, and players need to solve three problems to clear each level. The levels are grouped into three sets: Easy, Medium, and Hard. For each difficulty set, there are 32 levels. There is also a bonus set called Challenge where players need to find all the possible combinations that would yield 24, given the random numbers and operators.

The game is suitable juniors who are in Grade 3-8. In fact, there exists a complete set of Easy/Medium/Hard/Challenge with 112 levels for each Grade. All of these levels are unlocked from the start, allowing players to jump between levels to find the perfect difficulty level for their current learning stages.

Players try to fix Victor the Robot who’s been having problems with his head since he entered Door 24.

Parents Need to Know

The game is developed by Artgig Studio, the maker of the Mystery Math series. If you’re familiar with their apps, you can expect the same level of quality with Door 24 - Math. This game is currently available for free without in-app purchases.

If you’re wondering why the game uses 24 instead of other numbers, well 24 is the integer between 0 and 80 that has the most factors: 1, 2, 3, 4, 6, 8, 12, and 24. The next integer that has more factors is 84, but it would be too difficult for juniors to figure out all the combinations.

The Challenges sets require players to find all possible combinations, instead of just one.

Things I Like

The learning curves are well-designed across the 600+ levels. The difficulty increases gradually from two operands to four operands, from addition to division, and from basic understanding of order of operations to placing parentheses to yield the desired result.

I really enjoy the Chellenge sets in this game. They require players to find all possible solutions, given the random numbers and operations. Even adults would find it challenging.

Finally, you can trigger the math review popup that’s available on each non-Challenge level. The popup will provide brief explanations that could help you finish the current level.

The Math Review section offers a detailed explanation of the mathematical concepts required to complete the challenges.


Door 24 - Math is a great math game for juniors in Grade 3-8 to practice their arithmetic skills. By forcing players to come up with working combinations of operands and operators instead of simply calculating the result of an operation, the game is a great learning ground for juniors to expand their problem solving skills.

For juniors ages 7 and under, I’d recommend the Mystery Math series instead.

Door 24 - Math is available for iPad
Get it on the App Store: iPad

App was suggested for our honest review.