24

This is a challenging math game for kids (and okay, adults) that requires no materials except a pencil and paper. My sister-in-law Missy, our friend Beth, and I have played it with our (eight) kids on co-op day, and it never fails to stump at least one of us.

This is how we learned to play the game:

Write down the following numbers, either on a chalkboard or whiteboard or paper:

2, 3, 4, 5, 6, 7, 8, 9

Next, have the student (or yourself!) select four numbers—just circle them on the board.

2, 5, 7, 8

Now, the purpose of the game is find a way to use those four numbers–using addition, subtraction, multiplication, and/or division–to reach a result of 24.

And it works. No matter what four numbers you pick. It always, always works–somehow, someway, you can always reach the end result of 24. (Sometime this happens after much blood, sweat, and tears and insisting that nope, I happened to select the one combination of four integers that in fact will NOT result in 24 before one of your kids proves you wrong a minute or so later.)

This is one of those situations in which mathematics is a complete mystery to me. How is it that four integers between 2 and 9, no matter what they are, can always, without exception, be manipulated to reach the result of 24? I realize mathematicians out there completely grasp the perfect logic and reason behind it…but it never fails to blow my mind every time.

It also never fails to torture me when I am unable to solve one of the combos. (Missy and I try to do it along with our kids, and we often wind up cracking up at each other. It ain’t easy, man.)

Try playing this with your kids today! Select four numbers from 2, 3, 4, 5, 6, 7, 8, or 9 and use addition, subtraction, multiplication, and/or division to reach the result of 24.

And try to solve my example above! (And I’d like to thank those of you in advance who are going to solve that thing within seconds and make me feel like a dodo bird.)

(Note: the version we play omits the number 1 from the field, though I believe many versions include it. Also, the version we play prohibits using the same number twice, though I understand that other versions don’t have the same rule.)

Lemme know if you’ve played this before!

(If it takes you 4.3 seconds to solve each combo, you don’t have to tell me that part.)

Comments

• Roxanne

I’ve not played this but sounds fun… will give it a try!

• LaVonne

2×5=10
10-7=3
3×8=24

Cool game! Never heard of this before, but will definitely be playing it at family gatherings and game night! Especially with the kids.

(By the way, that combo above only took one try…about 3 seconds. đź™‚ I’m just sayin’ )

• Angie

took me a while… 2 x 4=8 + 7 + 9= 24

• http://leavehappier.wordpress.com Amber

Let’s see… (2 x 5 – 7) x 8 = 24
Did I do the order of operations correctly? I meant 2 x 5 = 10 – 7 = 3 x 8 =24.
Thanks for a fun way to start my Monday – I love puzzles. : )

• jenni

I haven’t found a solution using all four numbers but…
5 – 2 = 3 * 8 = 24
7 + 5 = 12 * 2 = 24

Does using only three of the numbers count?

• Kristi M-Texas

5 x 2 -7 x 8 = 24

• Sarah Kay

Took me a few minutes but I got it! Using all 4 numbers! Okay.. more than a few minutes.

• Andrea

Took me awhile, but I found an answer!
4, 5, 7, 9

(4×9)-(7+5)= 24!

That was definitely a brain teaser!

• Kristi M-Texas

[(5×2)-7] x 8 = 24

I should have included myparentheses!

• http://www.mamacitalujan.blogspot.com Joy

I’m so not a math person… I’ll give this ‘game’ to my 17 year old and see what she can do with it. đź™‚

• Sarah

This is HARD! I feel like I have tried ever combo. Can wait for someone to beat your example and post the winning combo.

• http://www.DaleFamilyFarms.com Andi

I taught math in the jr. high and high school for 14 years and there is also a commercial product (search 24 game) and they have lots of wonderful twists on this game! The original has 1-digit numbers and the cards are graded easy medium and hard. There is also a 2 digit box as well as fractions. Great mental math practice and good for pattern finding! And can be used at all differnt ages!

• Sarah L

We used to play this all the time in elementary school, but we called it Challenge 24 and used cards with 4 number combinations on it that you competed against each other to figure out. We even had school-wide competitions. I was half decent at it, but there were people in my class that weren’t necessarily great at math but were awesome at this game. They still sell the cards – http://www.24game.com/
(I couldn’t get this one for the life of me, so I think I’m way out of practice!)

• Laura W

The correct way to right it would be ((2 x 5) – 7)8. That tells you that you do the operations within the parenthesis first, and then multiply the answer by 8.

• Angie

I grabbed the wrong numbers… must be a Monday! đź™‚

• Sheri H.

Our son plays this at school….it has really helped with his math facts (even though he says he does not like this game :). Btw…he is in 6th grade.I think we will start having this as part of our game night with all the kids. Jack tried to explain it to me but now I actually understand what he was talking about!

I have to admit…it took me too long to figure it out so I just cheated and read the replies…it makes perfect sense now :).

• Whitney

Yes, Amber, you wrote that correctly. Order of operations dictates that multiplication be completed before subtraction. Laura W, your expression is also correct, however the parentheses around 2 x 5 are superfluous. Sorry if I’m being picky, but I’m a 20+ year veteran math teacher đź™‚

• Sara

I was the Challenge 24 champion in 4th grade lol. I haven’t played in FOREVER.

• laura h

Seeing the number in lights like that brought back emotions of watching the Indy race yesterday and seeing the number ’77. in lights.
When news reached the racetrack that Dan Wheldon had died from injuries from the horrific crash his number ’77’ was lit at the top of the score board and during the time the racerdrivers, still able to race their vehicles, ran their five track tribute running three deep the entire five laps.

Will copy off this game, fun for over the long winter months. We are supposed to have snow tomorrow here.

• Megan

Not to be mean, but what you wrote above one of the biggest pet peeves for math teachers everywhere. You have abused the equals sign horribly.

2 x 4 = 8

2 x 4 does NOT equal 8 + 7 + 9

• Krystal

We played this game in Elementary and Middle school too – we even had 24-game competitions with other schools. This was a big deal in 6th grade – everybody wanted to be the 24-game champion!

• Katrina in Seattle

We used to do something like this every week in elementary school, but I could’ve sworn that we used a wider range of numbers, and that the end number changed as well. Maybe we took the risk that there wasn’t going to be an answer? Does anyone know the rules of the game if using “more” numbers?

• Becky

My kiddos are in Catholic school where they have access to an Internet site called first in math. They have been doing a similar skill set series with just 3 numbers, but all functions. They are in grades 2 and 4 and most of the time they come up with the answers before I can. I’m proud of them but very worried about my own brain cells. Thanks, Ree, for making me feel better!

• Angela S

my two youngest children love math. I’ve printed this out and I have no doubt they will turn it into a race to see who finishes first!

• Mary Anne M

Took me a while as well. 2*5 = 10, – 7 = 3, * 8 =24.

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