🎯 Number Knockout

How to Play

The one rule that matters

Every number you rolled must be used exactly once in each sum. Roll 4, 5 and 2 and you may write 4 × 5 − 2 = 18, but not 4 + 5 = 9, because the 2 has been left out.

One roll, and that is your lot

You get one throw of the dice and then two minutes to make as many different numbers from it as you can. You do not roll again between answers — the whole skill is squeezing every number you can out of the three you were given. (If you manage every single one, this version does throw again, which the real one does not, because standing about for ninety seconds is no fun.)

Points are the numbers themselves

Knock out 12 and you score 12. Knock out 3 and you score 3. So the big numbers up the far end of the board are where the game is won, and it is usually worth spending time on 30 rather than hoovering up 1, 2 and 3.

Two ones and you throw again

A roll like 1, 1, 4 can hardly make anything, so the rules give you an automatic re-roll if more than one 1 comes up. This does that for you without asking.

The equals sign

You can write just the sum — 4 × 5 − 2 — and it will work out what that comes to and knock it off. But it is better to write the whole equation, 4 × 5 − 2 = 18, and say what you think it makes. Get it wrong and it tells you what it really comes to, which is the bit you learn from. Write only the sum and the computer has done the arithmetic for you.

Knocking one out

Make any number still standing on the board and it is crossed off. Each number can only be knocked out once, so once 18 has gone you need a different answer.

Signs you can use

Add, take away, times and divide, plus brackets to say what to do first. On the harder levels you also get powers and square roots.

Powers are free, and this is the big one

The little number you raise something to is not one of your dice — you choose it, and it does not count as using one up. So on a roll of 2, 3 and 4 you can write 2³ + 3² + 4² = 33, and all three dice have been used, as bases. But 2³ + 4 does not count, because the 3 was only ever an index and never a base of its own. Once you see this, the top half of the board opens right up.

Brackets are where the points are

4 + 5 × 2 is 14, because times happens before add. But (4 + 5) × 2 is 18. Same three numbers, different answer — and with a board of 36 numbers, moving the brackets about is how you find them.

Fractions along the way are fine

Only the answer has to be a whole number. 5 ÷ 2 × 4 is perfectly allowed: it goes through 2.5 and comes out at 10.

At the end

It tells you what else that last roll could have made. Sometimes it is one or two; sometimes it is fifteen and you will want another go.

On a keyboard

Type the digits and signs, R for a square root, Backspace to rub out, Esc to clear, and Enter to knock it out.

Where this game comes from

Number Knockout is played by Classical Conversations students, who run it as a national competition for 11 to 14 year olds. In the real thing two students face each other: one is the contender, saying their equations out loud, and the other is the challenger, whose job is to listen for mistakes. This is our own version, built to practise at home — so there is nobody to play against and nothing to say out loud, just you, the board and the clock. You can read about the real competition at classicalconversations.com.