1. Choose your operation.
Plus, Times or Mixed, and one of five levels. Tap Start to reveal the numbers and start the clock. The symbol in each small blue field tells you which operation to use.
Five answers.
One final equation.
Find the sum or product in five number puzzles. Your five answers become the puzzle in the centre.
Now also available on the Apple App Store.
Free. No ads. No tracking.
Watch the video
Five outer fields and the final equation in the center – one complete Mixed round.
Playing the video connects to YouTube. Watch on YouTube
How CALCTHRUM works
2. Find the right number.
Two numbers make a third. For 16 + 12 = 28, tap 28. The answer appears in the small blue field.
16 + 12 = 28
3. Solve the centre.
After five correct answers, those exact five numbers form the centre puzzle. Find the final answer and celebrate with confetti.
Your playing time. Your chosen voice.
The clock measures active playing time; each wrong attempt adds a 10-second penalty. Your statistics show best time, average time and solved rounds. Settings let you hear correct equations and choose German or English.
Language and sound
Ready for your first round?
Play in your browser on phone, tablet or computer. No account or installation needed.