Neon Sums Mental Math Game: Test Your Speed and Accuracy in 3 Modes
Neon Sums is a game of working out sums in your head, with no paper and no pen. Play a 60-second sprint, a 20-question time attack or survival, and combine any level with the operations you want. When a game ends, it shows which kinds of question slowed you down.
💡 About This Tool
The three modes end in different ways.
| Mode | Ends when | After a wrong answer |
|---|---|---|
| 60-Second Sprint | 60 seconds pass | Next question |
| 20-Question Time Attack | You get 20 right | 3 seconds added, same question again |
| Survival | Your time runs out | 2 seconds lost, next question |
You can also pass. In time attack that adds 5 seconds, and in survival it costs 2 seconds.
Survival starts with 10 seconds and caps at 20. Your first correct answer adds 4 seconds, and each one after that adds 5% less: about 2.5 seconds on the 10th, about 1.5 on the 20th, and about 1 from the 28th onward.
Each question scores base points × question type weight × speed bonus × boost. The speed bonus reaches 1.5 times at most. The boost grows with your streak: 1.5 times at 5 in a row, 2 times at 10 and 3 times at 20. A wrong answer or a pass resets it.
| Level | Base points | Target time |
|---|---|---|
| Lv.1 Easy | 10 | 2.5 s |
| Lv.2 Normal | 15 | 3.5 s |
| Lv.3 Hard | 20 | 5 s |
| Lv.4 Expert | 30 | 7 s |
Your rank comes from accuracy and average time. S needs 95% accuracy within 0.6 times the target, A needs 90% within 0.85 times, and B needs 80% within 1.2 times. Anything else is C, and so is any game with fewer than 5 correct answers.
Turn on chain questions and just over a third of the questions show three numbers, like (8 + 4) × 3. When there are brackets, work those out first.
🧐 FAQ
Q: Why does the game move on before I press OK? A: With "Check answers automatically" on, your answer is checked as soon as you have typed as many digits as the answer has. If you would rather not get that hint about the size of the answer, turn it off in Settings. Then Enter or OK checks your answer.
Q: What are the keyboard controls? A: Number keys to type, Backspace to delete, Enter to confirm, Space to pass, and Esc or P to pause. On the menu and result screens, Enter starts a game.
Q: Do divisions ever give decimals or remainders? A: No. Every division comes out exact, and subtraction answers never go below zero.
Q: What happens to the clock if I switch tabs? A: It stops when you move to another tab or window, and when you scroll the game off the screen. The time while stopped does not count.
Q: Can I play with my phone sideways? A: Yes. The question moves to the left and the keypad to the right.
Q: Can I delete my records? A: Press "Delete all records" twice in Settings. That removes your personal bests, history and question type totals, and keeps your settings.
📚 Fun Facts
Speed sums have their own world championship. The Mental Calculation World Cup began in 2004 in Annaberg-Buchholz, Germany, with 17 competitors from 10 countries. The town was a fitting choice: Adam Ries, the 16th-century author of popular German arithmetic textbooks, lived and worked there. The event has returned every two years since.
Its contests go well beyond the kinds of question here. Competitors add long lists of numbers, multiply large numbers and work out square roots, and the list of contests changes from one event to the next.