Math Puzzles

[Ducky Havok]

Well my friends math teacher gave him this list of 50 math puzzles, and he passed it along to me (since he knows I like them more). Out of the 50 I haven't solved 7 (I just got them this morning and worked on them through school), so I figured I'd post them on here for you guys to try. If you really want I'll put up all 50 later.

 

1. Use three 5's to make 115

2. Use four 8's to make 100

3. Use two 4's to make 24

4. Use four 7's to make 70

5. Use three 4's to make 50

6. Use three of the same number to make 28

7. Use three of the same number to make 13

 

I think most have done these kind of things before, but just in case I'll give some examples. For instance, Use six 9's to make 100:

[math]\frac{(999-99)}{9}=100[/math]

The only rule is you are only allowed to use that one digit, but you can use any mathematical symbols you want (such as exponents or factorials, even decimal (like .5)) Have fun!

[RedAlert]

Does the exponent have to be of the same digit too?

[Ducky Havok]

Yes you are only allowed to use that one digit, like three 3's to make 729, [math]3^{3+3}=729[/math]

[RedAlert]

OK. I will try and work on them.

[dan19_83]

1. 5! - [(sqr root 5) by (sqr root 5)] = 115

2. 88 divided by .88 = 100

3. (sqr root of 4 + sqr root of 4)! = 24

4. 77 - [(sqr root 7) by (sqr root 7)] = 70

5. 4! + 4! + square root of 4 = 50

6. 4! + [(sqr root 4) by (sqr root 4)] = 28

 

 

! = factorial

 

and sorry i can't use latex!!

[RedAlert]

Not allowed to use any numbers but 8.

 

Anyways I got number 7(Use three numbers to make 13): 12 + (12/12) = 13

[dan19_83]

that's what i did

[dan19_83]

Not allowed to use any numbers but 8.

 

Anyways I got number 7(Use three numbers to make 13): 12 + (12/12) = 13

 

That may be wrong cause you are using the numbers 1 and 2. single digit numbers only??? i'm not sure

[RedAlert]

that's what i did

sorry misread.

 

#6. 9.333333333 + 9.333333333 + 9.333333333 = 50

[RedAlert]

That may be wrong cause you are using the numbers 1 and 2. single digit numbers only??? i'm not sure

 

You can use it any way.

[RedAlert]

2. 88 divided by .88 = 100

5. 4! + 4! + square root of 4 = 50

 

A small math question, what does 4! mean?

[Ducky Havok]

on numbers 6 and 7 you are only allowed to use one number. Example, five numbers to make 100. 111-11=100. Good job on 2 and 5 dan19 83

[dan19_83]

4! means 4 factorial i.e.

4*3*2*1 = 24

[Ducky Havok]

4! means 4 factorial, which is 4 times 3 times 2 times 1.

[dan19_83]

keep an eye on post 5 by me. i'll edit it as i get more answers

[Ducky Havok]

dan, maybe you could use spoilers so others can try without accidently seeing it? Also, want the rest of them up?

[dan19_83]

i'll try and learn how to do that in future, sorry.

the last one is stumping me but that's because it's 4am here so i'm going to bed and i'll do it on the morning!!!

 

put up the rest if others request cause i know it'll take you a lot of time to write them out and it would be a waste of time for just one person

[RedAlert]

12 + 12/12 = 13 is not right??!! I used only one number, 12.....

[Ducky Havok]

No, you used the numbers 1 and 2. You have to think single digits

[Martin]

1. 5! - [(sqr root 5) by (sqr root 5)] = 115

2. 88 divided by .88 = 100

3. (sqr root of 4 + sqr root of 4)! = 24

4. 77 - [(sqr root 7) by (sqr root 7)] = 70

5. 4! + 4! + square root of 4 = 50

6. 4! + [(sqr root 4) by (sqr root 4)] = 28

 

 

! = factorial

 

and sorry i can't use latex!!

 

Dan did a great job getting numbers 1 thru 6. May I try number 7?

 

the question is how to use three copies of a number to make 13

 

 

[hide] 4! + sqrt 4 = 26' date=' so you can divide that by sqrt 4 and get 13

 

(4! + sqrt4)/sqrt 4 = 13[/hide']

 

these are nice puzzles D. Havok, hope you post more of this kind

[RedAlert]

Bah!

 

The grapes are too sour anyways.....

[Dak]

OH FOR F*** SAKE!

 

i only just realised that this is page 2, i thought that it was page 1 and that redalerts post was the op... you would not believe how long i spent trying to figure out in what dieviouse way a maths puzzle had been encrypted as 'the grapes are too sour anyways'

 

dammit.

[dan19_83]

OH FOR F*** SAKE!

 

i only just realised that this is page 2' date=' i thought that it was page 1 and that redalerts post was the op... you would not believe how long i spent trying to figure out in what dieviouse way a maths puzzle had been encrypted as 'the grapes are too sour anyways'

 

dammit. [/quote']

 

 

lol, i've been laughing my ass off for ages about this!!!

[RedAlert]

OH FOR F*** SAKE!

 

i only just realised that this is page 2' date=' i thought that it was page 1 and that redalerts post was the op... you would not believe how long i spent trying to figure out in what dieviouse way a maths puzzle had been encrypted as 'the grapes are too sour anyways'

 

dammit. [/quote']

 

HAHAHAHAHAHA!