How to play Mental Math (Siêu Tính Nhẩm): one sum, one number pad, fastest wins

A question step by step, the six levels, scoring, the number pad, awards and a classroom plan, for 1 to 50 players.

Updated 4 November 2026

Mental Math is a sum race for 1 to 50 players. Everyone gets the same sum at the same moment and types the answer before the clock runs out. Right and fast scores the most. Its Vietnamese name, Siêu Tính Nhẩm, means super mental arithmetic.

In GatherPlay's Mental Math each player types on their own phone, tablet or laptop. A shared screen, a TV or a projector, is recommended but not required: it shows the sum huge, who has answered and the reveal. The sum is on your phone too, so you never have to look up.

The goal

Have the most points after the last sum. You score by getting each sum right, and by getting it right fast.

A question, step by step

1. After a short countdown, everyone gets the same sum at the same time.
2. Work it out in your head and type the answer on the number pad.
3. Tap Send answer. You get one answer per sum and it can't be changed, so check the number before you send it.
4. The question closes when time runs out, when everyone has answered, or when the host skips it.
5. Then comes the reveal, about 4 seconds: the answer, each player's result, and the 3 fastest right answers. In a big room the shared screen shows how many were right, how many were wrong and how many did not answer, and the most common wrong answer.
6. Then the next sum.

The six levels

• Kids: adding and taking away within 10.
• Easy: adding and taking away within 20, and the 2 to 5 times tables.
• Medium: two-digit sums and differences like 48 + 37, every times table, and divisions like 63 ÷ 9.
• Hard: three-digit numbers, a two-digit number times a one-digit number, and missing numbers like 7 × ? = 56.
• Super: two-digit times two-digit, squares from 11 to 25, the order of operations like 3 + 4 × 8, and round percentages like 25% of 360.
• Genius: three-digit times two-digit like 348 × 27, squares from 31 to 99, cubes from 11 to 19, three-step chains with brackets like (48 + 27) × 6 − 125, four-digit numbers divided by two-digit ones, and percentages like 35% of 840.

Every answer is a whole number from 0 to 99999, and division always comes out even. The host picks the easiest and the hardest level, and the questions are shared out across that range, getting harder as the game goes on. The default is Easy to Super. Sums are made fresh for every game, so they never run out. Each screen writes division its own way: ÷ in English, : in Vietnamese, as in Vietnamese schoolbooks.

Scoring

• A right answer scores 500 points, plus up to 500 more for speed: the more time is left when you answer, the more you get.
• The streak bonus rewards right answers in a row: +100 for 2, +200 for 3, and so on, up to +500. A wrong or missing answer breaks the streak. The host can turn the bonus off.
• A wrong answer or no answer scores 0.
• Players with the same score share a rank.

The number pad and the keyboard

The game has its own number pad on every device, so your phone's keyboard never pops up. 1 2 3 are on the top row, C 0 ⌫ on the last, and a big Send answer button sits under them. C clears your answer, ⌫ deletes one digit.

• On a laptop the real keyboard works too: type the digits, with the numpad if you have one.
• Backspace deletes one digit. Escape or Delete clears the whole answer.
• Enter submits.

Awards and badges

At the end of the game there is a podium for the top 3, and four awards that belong to that game only:

• Fastest fingers: the shortest average time over your right answers, with at least 3 right.
• Sharpest: the most right answers.
• Longest streak: the longest run of right answers, at least 3 in a row.
• So close: the most answers off by exactly one, at least 2.

Players who are signed in also earn profile badges: Quick as a squirrel (fastest in the room on 5 questions in one game), Flawless sums (every answer right in a game of 10 or more questions), Prodigy (win a game that reaches Genius), Top of the class (win a game of 20 or more players) and Human calculator (80% or more right in 5, 25 and 100 games, for bronze, silver and gold). Badges count only games with players on at least 2 different devices.

Tips

• Right beats fast. A wrong answer scores nothing, while a slow right answer still scores at least 500.
• You can't change an answer, so glance at your number before you press Send answer.
• A streak is worth a lot late in a game: a fifth right answer in a row adds +400 on top of its points.
• Work from the left in big sums: 348 × 27 is 348 × 20 plus 348 × 7.
• A wild guess is cheap. No answer scores the same as a wrong one, so send something when the clock is nearly out.

In the classroom or at a team event

• Put the shared screen on a projector. A room holds up to 50 players when the game is Mental Math (other games hold 20), each on a phone, tablet or laptop.
• For younger children pick Kids to Medium, or just one level. Switch off × and ÷ if they have not met them yet.
• Give beginners 20 to 30 seconds per question. Quick drills fit 10 to 15 seconds, and Super and Genius sums usually need 20 to 30 seconds or more.
• Everyone answers at once, so nobody waits for a turn, and in a big room the reveal shows totals instead of every name.
• Switch the streak bonus off for a gentler game.

Start a game

1. Open GatherPlay on the TV or projector and host a Mental Math game.
2. 1 to 50 players join with the QR code on the screen.
3. Pick the number of questions, the easiest and hardest level, the operations, the time per question and the streak bonus, and start.