Math practice · reimagined
Absolute Value Game
This absolute value fight traps a subtraction between two bars, like | −7 − 10 |, with numbers from −15 to 15, and the answer is always positive. Race your rival to each distance: answer first to land the blow, and fast to make it hurt.
Ages 4–99+ · no download · plays in your browser · 23 languages
What is absolute value?
The absolute value of a number is its distance from zero on the number line, written between two straight bars. A distance has no direction, so it is never negative. Ride 4 floors up or 4 floors down in a building, and either way the trip is 4 floors long. That is why |4| and |−4| both equal 4.
Example: what is | −13 − 8 |?
- Start inside the bars: −13 − 8 means beginning at −13 and moving 8 further down.
- That lands on −21, so the bars now hold −21.
- The bars ask how far −21 is from zero, and that distance is 21.
- Your answer is 21, and you enter it on the keypad.
Learn it step by step
The two bars | | mean "how far from zero?" — and distance is never negative.
So |−7| is 7, because −7 sits seven steps from zero. Work out what's inside the bars first, then if it's negative, drop the minus sign. |3 − 8| = |−5| = 5.
Type the distance — always zero or positive.
Tips and common mistakes
- Read | a − b | as the gap between a and b on a number line. In | −3 − 5 |, that is 3 steps up to zero plus 5 more, so 8.
- A common mistake is erasing the minus signs before subtracting. | −6 − 4 | is not 6 − 4 = 2. Work inside first: −6 − 4 = −10, so the answer is 10.
- Check a weather forecast together and pick two temperatures, such as −4 °C at night and 6 °C at noon. How many degrees apart are they? | 6 − (−4) | = 10.
How to play
Each problem shows a subtraction locked inside two bars, such as | 8 − (−5) |, and the second level adds another pair, as in | −2 − 9 | + | 8 |. Type the positive result on the keypad. The first correct answer lets Onion attack, and the speed of your answer sets the strength of the blow.
— Quick answers —
Absolute: the short FAQ
- What is the modulus of a number?
- The modulus of a number is another name for its absolute value: the size of the number with its sign ignored. The modulus of −12 is 12, and the modulus of 12 is also 12, written |−12| = |12| = 12. Do not confuse it with modulo, a different word that means the remainder left after a division.
- How do you add two absolute values?
- Find each absolute value on its own, then add the two results. In | −11 − 3 | + | 7 |, the first bars hold −11 − 3 = −14, which becomes 14. The second bars give 7, so the total is 21. Do not put everything under one pair of bars first: | −11 − 3 + 7 | is only 7.
- Is there a trick for subtracting a negative number?
- Yes: subtracting a negative number gives the same result as adding the positive one. So 6 − (−14) is the same as 6 + 14, which is 20. A number line confirms it, because the gap from −14 up to 6 is also 20 steps. The trick matters inside absolute value bars too: | 6 − (−14) | is 20, not 8.
- Why does my child think absolute value changes the sign?
- Many children hear “absolute value removes the minus sign” and remember it as “absolute value switches the sign”, so they write |9| = −9. Bring the idea back to distance: 9 sits nine places from zero, so |9| = 9. The bars can take a minus sign away, but they never add one, so an absolute value is never below zero.
- Can a whole class play this absolute value math game for free?
- Yes, at no cost: both levels load in a browser on laptops, tablets or phones, and no pupil needs an account. For absolute value practice at the board, draw a number line from −10 to 10, mark −7 and 5, and ask how far apart they are. Then write | −7 − 5 | = 12 to show the gap as an absolute value. To follow each pupil’s progress, use the schools plan, priced per student, with its teacher dashboard.