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Four Fours

(121 Posts)
crun Thu 12-Mar-15 12:29:07

I thought I'd try you with a puzzle that our maths teacher Mr Garlick set us forty odd years ago, and see if it captures your interest or falls flat.

The idea is to write a formula for every integer between one and a hundred in terms of four fours. You can use as many mathematical symbols as you like, but the only numeral allowed is four, and you must use four of them, no more, no less. (As there's no correct character on the keyboard, use .4' for point four recurring.)

I'll start off with a few so you see the idea:

1= 44/44
2= 4/4+4/4
3= 4/4+4/sqrt(4)
4= 4/sqrt(4)+4/sqrt(4)

Let's do them in order, so that people don't cherry-pick all the easy ones first:

5= ???

hildajenniJ Thu 12-Mar-15 16:16:35

Please don't baffle me with sums! I think I have dyscalculia.

loopylou Thu 12-Mar-15 16:24:24

I'm sure I have it too........

crun Thu 12-Mar-15 16:39:17

"I don't understand your 9 either!"

sqrt4 =2
2*4 =8
4/4 =1
8+1 =9

alternatively:

9= 4+4+4/4

JoyBloggs Thu 12-Mar-15 16:40:20

crun Another question.... So, we can add, subtract, multiply, divide, use the square root and also this factorial thingy but I'm just wondering if there are any other 'processes' we can use that I'm not aware of?

crun Thu 12-Mar-15 16:55:13

Other than recurring decimals that I mentioned at the top, that's pretty much it apart from powers. You don't need to keep thinking in terms of just adding though, for example a much simpler way of getting ten is:

10= 44/4.4

(Hint: That ought to give you 11 very easily.)

rosequartz Thu 12-Mar-15 16:56:57

My head hurts.
I thought the answer was going to be 16!

crun Thu 12-Mar-15 17:03:21

How did you come up with 16?

10*4.4 =44

numberplease Thu 12-Mar-15 17:05:51

I didn`t even understand the question. I was complete rubbish at maths, wasn`t even allowed to take my maths GCE O level, because of the dismal mark I got in the mock exam!

numberplease Thu 12-Mar-15 17:06:14

I didn`t even understand the question. I was complete rubbish at maths, wasn`t even allowed to take my maths GCE O level, because of the dismal mark I got in the mock exam!

numberplease Thu 12-Mar-15 17:06:36

Ooops!

pompa Thu 12-Mar-15 17:06:37

the only power you can use is 4 as to write any other power 2,3 etc would require writing a superscript 2 or 3.

crun Thu 12-Mar-15 17:12:11

I've used a power other than 4, but there may be an alternative way that avoids it. For most of the numbers there are umpteen answers.

soontobe Thu 12-Mar-15 17:19:13

I dont know what superscript means.

I am still struggling with 11, but dont mind persevering.

pompa Thu 12-Mar-15 17:31:13

4² this is how 4 squared would be written (4x4) The small 2 is superscript.

crun Thu 12-Mar-15 17:33:11

Superscript is a small sized text added at the top right of the main full sized text. (Subscript is bottom right).

crun Thu 12-Mar-15 17:37:27

How did you manage that pompa? I was trying to do a demo by cutting and pasting from MS Word, but it didn't work.

pompa Thu 12-Mar-15 17:43:26

I c/p from OpenOffice, but I cannot find a superscript 4.

crun Thu 12-Mar-15 17:49:10

You don't actually need any powers until 60.

soontobe Thu 12-Mar-15 18:03:52

I give up on 11.

crun Thu 12-Mar-15 18:14:15

11= 4/.4+4/4

If you ring the changes on that theme it will get you all the way to 18.

apricot Thu 12-Mar-15 19:06:55

I don't do numbers. Maths to me is just gibberish, the way letters are to dyslexics. This seemed very important when I was 16 but never has since.

Anne58 Thu 12-Mar-15 19:47:46

apricot I was just about to post "I don't do numbers" when I saw you had beaten me too it. grin

I'll stick with words, if that's ok. I like words, they (usually) don't make your brain hurt.

pompa Thu 12-Mar-15 19:53:19

12 = 4! - 4 - 4 - 4

rosequartz Thu 12-Mar-15 20:30:19

crun how did you come up with 16?

The OP title is Four Fours
Doesn't 4x4 =16?

Or not? confused now
A long time since I took GCE 'O' level (and passed) hmm

Ana Thu 12-Mar-15 20:33:23

I thought this thread was going to be about times tables before I read the OP rosequartz...confused