I have 10 points safely locked away with a 4 digit combination lock?

Question

if you add together the 2nd and 3rd digits you get the 1st digit, if you then subtract the 3rd digit from the 2nd and subtract the answer from the first digit you get the 4th digit. first person with the correct combination gets the 10 points.

I know there are lots of possible answers but there is only one correct one! list of possible answers dont count (my question, my rules!)

Ok, i never claimed that this was anything more than a guessing game with a mathamatical twist but as i seem to have upset some of you i will add a few clues. There are no repeat numbers, the 3rd number is half the 4th number and the 1st & 2nd numbers are odd numbers.i hope that helps but to be honest i wish i hadnt asked the question as some people seem to take things way to seriously!

this is it ! final clue (or giveaway to be precise!). Bmp1ksh,a+c & b+c = 10 points

Ok, no one has answered with just the correct combination which was 7524 so the 10 points will go to the first person who listed the correct code amongst the possible answers!

Answer 1

a=b+c
a-(b-c)=d

This is not deterministic. Multiple solutions are possible:

0 0 0 0, 1 1 0 0, 2 1 1 2, 2 2 0 0, 3 2 1 2, 3 3 0 0, 4 2 2 4, 4 3 1 2, 4 4 0 0, 5 3 2 4, 5 4 1 2, 5 5 0 0, 6 3 3 6, 6 4 2 4, 6 5 1 2, 6 6 0 0, 7 4 3 6, 7 5 2 4, 7 6 1 2, 7 7 0 0, 8 4 4 8, 8 5 3 6, 8 6 2 4, 8 7 1 2, 8 8 0 0, 9 5 4 8, 9 6 3 3, 9 7 2 4, 9 8 1 2, 9 9 0 0

Based on the "new clues", the possible answers are:

5 3 2 4
7 5 2 4
9 5 4 8
9 7 2 4

or, if you allow for "negatives" in the 3rd-2nd calculation (which I didn't in my list above):

3 1 2 4
5 1 4 8
7 3 4 8

Your last clue makes no sense. If the 1st and 2nd number are both odd, then the 3rd has to be even... so the 2nd+3rd has to be odd.

Answer 2

First Digit = 4
Second Digit = 3
Third Digit = 1
Fourth Digit = 2

Add 2nd and 3rd = 3+1 = 4 >> First Digit
Subtract 3rd Digit from 2nd Digit = 3-1= 2
Subtract Answer (2) from First Digit= 4-2=2 >> Fourth Digit


Also 0-0-0-0 works just as 4-3-1-2

I hope I could get 10 points for that
Thanks!

Answer 3

combination = abcd
b+c = a

a - (b - c) = d
b = a+c-d

b + c - b + c = d
2c = d so c must be either 0, 1,2,3 or 4

try:
if c is 0, d is 0, b = a+0-0 and b = a -0
so you could have: 0000, 1100, 2200, 3300, 4400, 5500, 6600, 7700, 8800, 9900

if c is 1, d is 2, b = a +1-2 and b = a - 1
so you could have : 9812, 8712, 7612, 6512, 5412 4312, 3212, 2112, 1012.

if c is 2, d is 4, b = a+2-4 and b = a-2
so you could have: 9724, 8624,7524,6424,5324,4224,3124,2024

if c is 3, d is 6, b = a+3-6 and b=a-3
so you could have: 9636, 8536, 7436, 6336, 5236, 4136, 3036.

if c is 4, d is 8, b = a+4-8 and b = a-4
so you could have: 9548, 8448, 7348, 6248, 5148, 4048.

There are many combinations to you lock.
9900, 9812, 9724, 9636, 9548, 8800, 8712, 8624, 8536, 8448, 7700, 7612, 7524, 7436, 7348, 6600, 6512, 6424, 6336, 6248, 5500, 5412, 5324, 5236, 5148, 4400, 4312, 4224, 4136, 4048, 3300, 3212, 3124, 3036, 2200, 2112, 2024, 1100, 1012, 0000
All of these meet your requirements.

If there are no repeating digits the list shortens to :
9812, 9724, 9548, 8712, 8624, 8536, 7612, 7524, 7436, 7348, 6512, 6248, 5412, 5324, 5236, 5148, 4312, 4136, 3124

You need more info to open this lock!

NOTE: Your rules are dumb. There is no point to guessing. I suggest everyone give this guy a minus.

Answer 4

There are 40 combinations:

0000
1012
1100
2024
2112
2200
3036
3124
3212
3300
4048
4136
4224
4312
4400
5148
5236
5324
5412
5500
6248
6336
6424
6512
6600
7348
7436
7524
7612
7700
8448
8536
8624
8712
8800
9548
9636
9724
9812
9900

With a 2.5% chance, I'm going to pick...

--> 8536

Answer 5

Mmmmm! I was useless at Maths when I was at school, and 30 years later, I find that I'm still useless at maths! Nope! Doesn't mean a thing!
At least I'm not going to get sent to detention for not doing this one!

Answer 6

ABCD

b+c=a
a-b+c=d

2c=d
d=0,2,4,6,8
c=0,1,2,3,4

0 0 b=0 to 9
a=1 to 9
there are 5 possiblilities for c,d: for each possiblility there are 9,9,8,7,6 choices for a,b = 39 possible answers.

Did you make this up or did you copy your homework wrong?

Answer 7

Let the digits be a b c d
b+c = a
a-(b-c) = d
(b+c):- b:- c:- a-b+c:-
(b+c):- b:- c:- (b+c)-b+c
Digits are:- (b+c):- b:- c:- 2c:-
Trial & error 5 3 2 4

Answer 8

there are 31 possible answers, I`m not listing them all for a lousy 10 pts (well i might later if noone else answers)

Answer 9

5-3-2-4 ... OK so i wasn't first but i only just found it and i worked it out all by myself!

Answer 10

too much thinking involed - i'll just take the 2 points...but interesting to see how many coorrect answers you get...