• Hey Guest. Check out your NeoGAF Wrapped 2025 results here!

Math Riddle? Solve it!

Status
Not open for further replies.
Stuggernaut

Stuggernaut

Grandma's Chippy
Ok so my daughter asks me a math riddle of sorts...and challenges me to solve it. I am thinking she is just trying to get me to do her homework so I say "no way I'm falling for that".

After she leaves, I am astumped trying to solve it..hehe

The riddle is...

Using ONLY +, -, x, /, (, ) symbols....create the numbers 0-10 using ONLY four 2's

I have all of them but 7 and 9....

1 = (2x2) / (2x2)

2 = (2/2) + (2/2)

3 = (2+2+2) / 2

4 = (2+2+2) - 2

5 = (2+2) + (2/2)

6 = ((2x2) x 2) - 2

7 = ?????

8 = 2+2+2+2

9 = ?????

10 = ((2x2) x 2) +2
 
You haven't done zero.. but that ain't hard:

(2+2) - (2+2) = 0

I think 0.2 is illegal... says nothing of using (.)
 
We used to do a game like this in middle school. Each graduating class had to take the number of that graduating year (ie. 1994) and create the numbers 1 through 100 using nothing but mathematic oprtations and properties. Pretty cool, but i really wish i knew what they did when they hit the year 2000. :lol
 
Apple Jax said:
Squares are allowed... I've spent the last 10 minutes trying to figure out 7 with a square.

No go...
Click to expand...

Where'd you see that squares were allowed? The original post only mentions *-/+().

However, if squares were allowed, then:

((2+2)²-2)/2 = 7
or
2²+2²-(2/2) = 7
 
(2²) + (2/2) + 2 = 7

but that's 5 (2's).


2x + (2/2) + 2 = 7
if x = 2

Technically I have 4 2's in the equation though it'll be a 5th when it's all said and done.

I'll try another one.
 
Who said sqaures or algebra could be used anyway? The rules are pretty explicit -

Using ONLY +, -, x, /, (, ) symbols....create the numbers 0-10 using ONLY four 2's
Click to expand...

By those rules it cannot be done. As for 9, it's a bit cheeky but technically ok.
 
A square is easily fixxed with an (x) since I counted it as a 2. However, if algebra isn't allowed, then a 7 is impossible, even when I was trying to start with a negative ((-2/2) + 2 = 1 << that should count as well :P) it'll take more than a few extra 2's to work.

It's impossible.
 
I suppose you could do it like that, as 'x' is an allowed symbol and the OP makes no mention of x explicitly meaning multiplication. It is definitely the best answer so far.
 
xabre said:
I count five and six '2's' in those solutions, the limit is 4.
Click to expand...

Well, the thing is, that isn't really a "2" in the numerical sense. Sure, it's drawn as a 2, but it's just there to denote a function, like any other symbol. Depending on your interpretation of the original question, it could have just meant that you could only use four twos for the values.

Either way, it's moot, since squares aren't allowed either way.
 
yudaan said:
A square is easily fixxed with an (x) since I counted it as a 2. However, if algebra isn't allowed, then a 7 is impossible, even when I was trying to start with a negative ((-2/2) + 2 = 1 << that should count as well :P) it'll take more than a few extra 2's to work.

It's impossible.
Click to expand...

Yeah, I'm thinking 7 is impossible if we follow the original rules exactly.
 
yudaan said:
A square is easily fixxed with an (x) since I counted it as a 2. However, if algebra isn't allowed, then a 7 is impossible, even when I was trying to start with a negative ((-2/2) + 2 = 1 << that should count as well :P) it'll take more than a few extra 2's to work.

It's impossible.
Click to expand...

Actually, you could do it with just one extra 2:

(2*2*2)-(2/2)

But yeah, I'm starting to think it's impossible, or it's really, really hard.
 
While that is true, but if I started with a negative 2, then it'll take more than a few extra 2's, which goes against proper thinking (doesn't stop me from trying though).

And 11 is just as, if not as, impossible to do than 7. 12 is done in a similar way to 9 ( (22+2)/2 = 12 ).
 
Saying a sqaure is just a function is meaningless. So are any of the other operands. It denotes "to the power of 2" That 2 isn't just a symbol, it has a relation to "2"

I can't figure this one out 7 either. And I don't see "." as an allowed symbol, so no dice with the decimal place-- but I don;t see why you couldn't use a negative.
 
Ignatz Mouse said:
I can't figure this one out 7 either. And I don't see "." as an allowed symbol, so no dice with the decimal place-- but I don;t see why you couldn't use a negative.
Click to expand...

Using ONLY +, -, x, /, (, ) symbols....create the numbers 0-10 using ONLY four 2's

The coma is there mate :)
there fore ,2 or .2 should be fine.. I personally like the 22 as two 2s. Very clever IMO.
 
Shompola said:
Using ONLY +, -, x, /, (, ) symbols....create the numbers 0-10 using ONLY four 2's

The coma is there mate :)
there fore ,2 or .2 should be fine.. I personally like the 22 as two 2s. Very clever IMO.
Click to expand...
The comma is used to seperate the different symbols we're allowed to use.


In other words:
+ - * / ( )

(* = x)

And in math, only the decimal symbal may be used for fractions.
 
Really? Ahh makes sense but then the original author didnt type it properly.. I saw (,) as explicity stating it is a coma used in math hehe.
 
haha, I hadn't thought about ++. Thats certainly an answer, though there is no way its the intended answer (if one exists)
 
Status
Not open for further replies.

Similar threads

Maze: Solve the World's Most Challenging Puzzle
8
671
kevboard replied
  • Poll
Can you solve a Rubik's Cube?
2 3
100
5K
nkarafo replied
The Yogurt Shop Murders case, over 30 years cold, appears to have finally been solved
17
631
DragoonKain replied
Ozempic. Does it work?
2 3
105
2K
Baemono replied
The Big Lebowski (first time watching it since it’s initial release)
27
233
Durien replied
Top Bottom