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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= ???

crun Fri 13-Mar-15 13:29:06

"26 = 4! + sqrt4 - sqrt4 + sqrt4"

Or, more simply:

26= 4! + sqrt4 - 4 + 4

27 = 4! + sqrt4 + 4/4

but if you have a look at this one, it will give you a few hints for some of the remaining ones:

27 = 4/.4' * sqrt(4/.4')

crun Fri 13-Mar-15 13:37:32

Another hint is to not look at each number individually. When you get the solution to one number it presents you with the answer to a whole group of others just by taking the same formula and swapping round a few +/- signs, or inserting/removing a few square roots. (You get 28 from 26 that way.)

soontobe Fri 13-Mar-15 14:28:45

My brain unfortunately does not work that way crun.

JoyBloggs Fri 13-Mar-15 14:41:17

28 = (4!+4)×4/4

JoyBloggs Fri 13-Mar-15 14:54:45

29 = (4!+4)+4/4

pompa Fri 13-Mar-15 15:03:01

No more hints please, it is spoiling it.

pompa Fri 13-Mar-15 15:04:38

30 = 4! + 4 + sqrt4

Alygran Fri 13-Mar-15 15:13:59

31 = 4!+sqrt4+(sqrt4/.4)

JoyBloggs Fri 13-Mar-15 15:19:34

32 = (4×4)+(4×4)

feetlebaum Fri 13-Mar-15 15:42:39

You're all insane...

feetlebaum Fri 13-Mar-15 15:43:36

To quote Fran Lebowitz, "In the real world, there is no such thing as algebra".

Nelliemoser Fri 13-Mar-15 15:47:30

??? confused I just about get what you are trying to do here. I only got 25% at GCE maths. I just can't do these things without needing a great deal of time to work them out.

Crun Would you like to attempt the 24 rows involved in my cable knitting pattern repeats while I try your calculations? wink

We all have our individual skills. Maths is not mine.

pompa Fri 13-Mar-15 20:27:23

33 = 44 - 44/4

pompa Fri 13-Mar-15 20:28:27

Knitting is the work of the devil

Greenfinch Fri 13-Mar-15 21:11:08

Whaaaaat?..confused

Ana Fri 13-Mar-15 21:15:53

I'm no good at maths either, which is why I'm leaving this thread to the experts!

crun Sat 14-Mar-15 00:16:42

pompa, that's five fours.

33 = 4!+sqrt4*sqrt4/.4’

pompa Sat 14-Mar-15 08:04:20

I shall go stand in the corner

absent Sat 14-Mar-15 08:07:21

Yes I can but I can't be bothered.

Alygran Sat 14-Mar-15 08:12:04

34=4!+4+(4!/4)
My 33=4!+(sqrt4/.4)+4

Ariadne Sat 14-Mar-15 09:44:35

Theseus is on his fourth sheet of A4; he says he had forgotten this and is thoroughly enjoying it..confused His degrees are in Maths etc. which is why he finds it fun. So thank you! Makes a change from the Killer Su Doku, he says!

crun Sat 14-Mar-15 11:58:36

Ariadne & Theseus

I had to Google those two, but I should have remembered them, they remind me of Mr Garlick again. When he wasn't teaching us maths he was trying to teach us Latin, and when he got fed up of banging his head against the wall he gave up and read us Greek mythology instead.

The Latin class was chaos, there was one kid who wanted to be a doctor, another who wanted to be a lawyer, and 28 who didn't want to be there at all because they'd chosen to do German instead.

soontobe Sat 14-Mar-15 18:09:30

Give up. Cant do 35.

soontobe Sat 14-Mar-15 18:10:43

36 = 4! +4 +4 +4

crun Sat 14-Mar-15 20:01:03

35 = 4!+sqrt4+4/.4’