Boxsum: Number Sum Puzzle

Count rectangles that add up

Only for iPhone

Expected Nov 16, 2026 · Free · Designed for iPhone. Not verified for macOS.

iPhone

Today's Daily is ready: one board, the same for everyone. Count every rectangle that adds up to the target, then see how your time compares. Boxsum is a number puzzle you solve by counting. You get a grid of numbers and a target. Find every rectangle of cells whose numbers add up to the target, then type how many there are. Drag across the board to box the ones you have found. You get three guesses, and a wrong one adds 30 seconds. Then the answer draws itself: every right rectangle, one pen stroke at a time. It sounds simple. Then two rectangles overlap, a blank cell quietly pads a sum, and you were sure there were seven. HOW IT PLAYS - Drag to box a rectangle. Marks are your own notes; they never answer for you. - Type your count. Three guesses. - Watch the reveal and see the ones you missed. A short practice board teaches the rules the first time you open the app. FOUR LEVELS - Easy: small boards to learn the trick. - Medium: 4 x 4 and up. - Hard: odd shapes and negative numbers. - Expert: fractions, decimals, three-digit numbers and big boards up to 8 x 9. The game picks your next board to match your speed. A DAILY BOARD One board a day, the same for everyone. A week strip lights the days you played. Five days out of seven makes a full week, so one missed day does not wipe out your week. Your best streak and a month calendar keep the record. SPEED THAT MEANS SOMETHING Every ranked board is timed by the server, not by your phone, and has its own list of fastest times. After a few ranked boards you get a speed rating that compares you with every player on every board, and it moves with each board you play. Only your first try is ranked. Replay any finished board as practice. MADE TO FEEL LIKE PAPER An exercise book on a desk: graph-paper boards, fountain-pen ink, the teacher's red pen for the verdict, and a gold star only when you beat your own best. Soft piano notes and haptics as the answer is drawn. Light mode, or the night desk in dark mode. NO ACCOUNT NEEDED Play every board as a guest. Sign in with Apple or Google if you want your name on the boards, your times kept and a place in the weekly points race. It is the same game and the same boards as boxsum.charlx.com, so you can also play in a browser. Free, with no ads, no purchases and no tracking. In English, Traditional Chinese and Korean. Made by one developer in Taiwan.

The developer, Charlrs Tsai, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Linked to You

    The following data may be collected and linked to your identity:

    • Contact Info
    • User Content
    • Identifiers

  • Data Not Linked to You

    The following data may be collected but it is not linked to your identity:

    • Usage Data

Privacy practices may vary, for example, based on the features you use or your age. Learn More

Accessibility

The developer has not yet indicated which accessibility features this app supports. Learn More

Information

Seller
Charlrs Tsai
Size
5.8 MB
Category
Puzzle
Compatibility
Requires iOS 26.0 or later.
  • iPhone
    Requires iOS 26.0 or later.
  • Mac
    Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
  • Apple Vision
    Requires visionOS 26.0 or later.
Languages
English and 2 more
  • English, Korean, Traditional Chinese
Age Rating
4+
Copyright
© 2026 CharlX
  • Developer Website
  • Privacy Policy

    • More by Charlrs Tsai