cracking numerical codes

[BillGatesJR]

What are the best techniques a person to use to guess a four digit number? I want to open a safe that has a keypad.

I have a talent for cracking three digit combinations, but the same principle doesn't not apply very well on 4 digit locks. For a 3 digit lock, I always start by doing the ten values first, then the one values. For instance:

Start at 000
Then try 010
020
030
040
050
060
....
....
990.

After that, if none of those numbers opened the lock, you start at 001 and continue:
002
003
004
005
006
007
008
009
011

You can skip every ten based value because you already eliminated every possible ten number. This makes cracking 3 digit numbers quick and easy.

My "tens and ones" method works like a charm with 3 digit codes, but I've noticed that this method is not as efficient for 4 digit codes since you have to take into account the fourth digit.

So my question to all of you math geniuses is, what is a good method for 4 digit number guessing?

[Zip]

Technically, completely random. May not be feasible if you're trying to crack a safe.

[Mantikore]

how does the method for 3 digits work? wouldnt it be the same as if you just counted from 000 to 999?

[BillGatesJR]

how does the method for 3 digits work? wouldnt it be the same as if you just counted from 000 to 999?

Technically speaking, yes it would be the same. But that doesn't change the fact that this method is faster than counting upwards from 000.

This is because you are separating each possible combination from 000-999 into sets of numbers based on their digit values. It is more efficient because you have already eliminated any combination that ends in zero before you begin counting up by one. So even if you still have to count up by one, you can skip the numbers that have 10 as a factor (ie. 500, 420, 310, etc.).

But, often times you will have the correct code before you even begin counting by ones, that's why it's faster. For some reason people are just more likely to pick combinations that end with a zero.

[mrgoodbar]

I would start with a set of combinations of non-consecutive numbers in which each element is unique like {3,6,1,2} {4,1,8,4}

What is the name of a set with no repeating elements?

[mrgoodbar]

but a four digit combination has 100,000 possibilites. Even if you make a list starting with the most likely it would prolly take you atleast 10,000 trys

[BillGatesJR]

but a four digit combination has 100,000 possibilites. Even if you make a list starting with the most likely it would prolly take you atleast 10,000 trys

No it doesn't. 4 digit combinations have 10,000 possibilities (0001-9999 plus 0000).

I would start with a set of combinations of non-consecutive numbers in which each element is unique like {3,6,1,2} {4,1,8,4}

What is the name of a set with no repeating elements?

What do you mean by this?

[eunux]

What is the name of a set with no repeating elements?

It's called a set.

[mrgoodbar]

o ill be damned it is 10000

[Ford Prefect]

All safes have the same last number.

C4.
http://www.qinetiq.com/home/newsroom/news_releases_homepage/2007/2nd_quarter/qinetiq__shell_and.Par.54180.File.tmp/Shaped%20Charge%20illustration.JPG

[Irukanji]

Assume no numbers are repeated. Also assume the number 1-4 are the first, and 0 isnt the last number.

Also assume it is an odd number.

Its much easier if you can catch a glimpse of it. Knowing 1 number can reduce the possibility of it being wrong, etc.

Most of the codes i know start with either 2 or 4, and end with either 6, 7 or 9.

Just wipe the key pad, put some graphite on it, then when they press the buttons, it will remove some of the graphite.

Knowing the first 4 numbers will still leave you with 10 possible codes..

[Irukanji]

Or use a baseball bat and wait for him to open the safe, then bash his head in.

[BillGatesJR]

Or use a baseball bat and wait for him to open the safe, then bash his head in.

Yeah that will probably be the easiest, and most cost efficient.:)

But then, what about the dead body? Kamisama can take care of that....what do you say buddy? lol