King of 20

App review by
Debbie Gorrell, Common Sense Media
King of 20 App Poster Image
Addictive math game teaches strategy over accuracy.

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The parents' guide to what's in this app.

Educational Value

Kids can learn about strategies for writing numerical expressions and simplifying. Though the game promotes the use of arithmetic and critical thinking, kids are not supposed to follow the order of operations as they play. This violates a fundamental math practice, so it's in direct conflict with what most kids are required to do in math class. In terms of developing math fluency and having fun, however, King of 20 is a compelling numbers game.

Ease of Play

Actual gameplay is easy, but reading and figuring out the rules takes some time.

Drinking, Drugs & Smoking

What parents need to know

Parents need to know that King of 20 is a math game that encourages kids to think strategically while arranging tiles on a board to form mathematical expressions; the expressions must come as close to 20 as possible when simplified. The game is challenging and promotes the use of math concepts, but some of the instructions conflict with practices kids use in math class, such as using the order of operations. Read the app's privacy policy to learn about the information collected and shared.

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What's it about?

In KING OF 20, which is based on a board game, kids start by choosing a beginner or advanced level for the computer opponent. Kids are challenged to make an expression using number and operation tiles that create a solution as close to 20 as possible. They get points for anything greater than 20, and the lowest score wins. Kids can add tiles to an existing expression, but they're not allowed to create negative numbers, and they're not supposed to follow the order of operations. For example, students may be given the numbered tiles 2, 3, 1, 6, and 8 and two tiles labeled "Plus." They can form the expression "8 Plus 6" to get as close to 20 as possible with the given tiles. On another turn, kids have the option to add tiles to this expression to get closer to 20. If they can't create an expression, they can pass or swap tiles, but there's a penalty. When the tiles run out, the player with the lowest score wins.

Is it any good?

This game is a stimulating way for kids to practice math skills, but the instructions to ignore the order of operations and only use positive integers reduces its learning value. Creating the expressions is addictive, especially when they get longer as gameplay progresses, and it's helpful that kids get to experience math in a fun setting. However, more variation in the operation tiles would reduce frustration, as it gets fairly impossible later in the game if you can only subtract or create fractions. The computer opponent also requires a lot of "think" time, which might put off some kids (and adults). Improving the rules to better reflect mathematical accuracy would give kids more consistency between what they learn in school and in this engaging game, and polishing the user experience would improve the solid premise.

Talk to your kids about ...

  • Families can talk about the strategies that kids use while playing and which ones work best.

  • Take turns and challenge kids to earn the lowest score.

  • Have kids simplify expressions they create in the game, but have them do it following the order of operations. Discuss whether or not the results are different and why.

App details

  • Devices: iPhone, iPod Touch, iPad
  • Subjects: Math: addition, arithmetic, division, multiplication, subtraction
  • Skills: Thinking & Reasoning: logic, solving puzzles, strategy, thinking critically
  • Price: Free
  • Pricing structure: Free
  • Release date: October 4, 2015
  • Category: Education
  • Size: 45.90 MB
  • Publisher: Ishmael king
  • Version: 1.2.1
  • Minimum software requirements: iOS 6.0 or later
  • Last updated: December 10, 2020

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