Blink and Add — Flash Mental Math Game

Numbers blink. Add, subtract, multiply or divide.

Mental math
4 min
Medium

Numbers flash on screen for about a second each, and then you answer. You are told the operation before the numbers appear — add, subtract, multiply or divide — so your memory goes to the numbers themselves. Early levels flash three two-digit numbers to add; later levels bring in the other operations, more numbers and faster flashes. It needs a free HumanCalc account.

Blink and Add is free with a HumanCalc account

Numbers blink. Add, subtract, multiply or divide. Make a free account in about 10 seconds (Google, one tap) and start playing right away. New accounts get a one-time +500 XP welcome bonus, and your scores, XP and streak are kept on every device.

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How it works

Try it

You will see Add, then 3 numbers will blink by, one every 1 second. Add them up in your head.

How to play

1
Read the operation
Each round starts with a label — Add, Subtract, Multiply or Divide — before any number appears. Use that moment to get ready.
2
Watch the numbers blink
The numbers appear one at a time in the same spot. Level 1 shows each for 1,000ms. For 27, 18 and 35 with Add, think 27 → 45 → 80 as they go.
3
Type the result
Enter the total, difference, product or quotient. For Subtract, take the rest away from the first number. For Divide, the first number is divided by the second and always comes out exactly. A wrong answer costs a life.

What it trains

Compute fast without writing anything down. Studies of mental arithmetic describe working memory as the place where numbers and partial results are held while you calculate. Blink and Add asks you to hold a few numbers and combine them; a level score measures performance in this game, not a general ability.

Practice focus: Mental math
Based on: DeStefano & LeFevre, 2004

Research background

DeStefano & LeFevre (2004): The role of working memory in mental arithmetic

These sources describe related tasks or concepts. HumanCalc adapts them for browser practice; a game score is not a clinical result.

Leaderboard

Weekly season resets every Monday. Scores show as Lvl 5.

Leaderboard

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Questions

Which operations are in the game?

Levels 1 to 3 are Add only. Subtract joins at level 4, Multiply at level 6 and Divide at level 8. Subtract always starts from the first number and never goes below zero. Divide always comes out as a whole number.

How fast do the numbers flash?

Level 1 gives each number 1,000ms. Level 10 gives 550ms. A brief blank ends each flash, so two equal numbers in a row still look like two flashes. Rounds grow from three numbers to as many as 6.

How does the level change?

Levels 1 to 3 advance after one correct round; from level 4 you need two correct rounds in a row. Two wrong answers in a row lower the level. You have three lives, and a wrong answer costs one.

Do I need an account to play?

Yes. Blink and Add is one of the games that needs a free HumanCalc account, which also saves your best level, XP and streak.