# Reverse Engineering Computer Formula

A computer uses an unknown formula to create a 4 digit Output using specific Input. Here are 3 examples:

Input = 20066 : 020470 : 47 : 1 : 322267 Output = 0927

Input = 20066 : 020470 : 46 : 3 : 198684 Output = 3244

Input = 20066 : 066992 : 20 : 3 : 307608 Output = 9055

Input (from left to right) in the first set is always 20066. The second set is always 6 digits long with the first number always starting with 0. Third set is always 2 digits from 01-99. Fourth set is always 1 digit from 0-9 and fifth set is always 6 digits long from 000000-999999. The output is always 4 digits long from 0000-9999.

Given the 3 examples above, if I only know the Input, how do I calculate the Output in the example below? Note: All the examples above and below are real rather than made up by me for example purposes. So, the Output in my example below should in fact be calculable using the Input somehow. I'm curious if there's "A Beautiful Mind" on this website that can actually see the formula or pattern to get the Output from the Input or explain how I can go about calculating this (if at all possible)?

Input = 20066 : 000308 : 15 : 7 : 957241 Output = ?

Also, would it help to figure out the formula if I had two different Input sets with both Inputs having the exact same Output? For example, if two of the three examples above had an Output of 0927, would that greatly help in figuring out the formula and if so, how?

Thank you!

• You can't: there are infinitely many formulas that could output the given numbers. (Even if you restrict the formulas to be linear, you could find a linear function of your inputs that gives any result you like for the output.) – Deusovi Mar 31 at 20:05
• (And if this is in a computer context, as it seems to be, it is very likely that the function is a hash function -- which would be designed to have unpredictable outputs, meaning we would likely not be able to easily reconstruct it.) – Deusovi Mar 31 at 20:07
• ... Also, this doesn't seem to be a puzzle; it might be a question you're curious about, but not every confusing question is a puzzle as we use it here. This likely doesn't have a "solution", and it doesn't seem to me to be related to puzzles in any way. So this question is likely off topic here. – Deusovi Mar 31 at 20:19
• This is in fact a puzzle because I'm certain it can be figured out (although maybe not easily) since it's calculated by a computer and I know the answer to the Output in the last example. I can provide many more Inputs with their known Outputs that use the same Input structure. I'm trying to figure out how the computer calculates the Output using the Input provided. – wonderfulsomebody Mar 31 at 20:31
• Perhaps the question is from an intelligence test or something and there's supposed to be a single simplest/clearest thing that the computer might be doing? @wonderfulsomebody, can you tell us something about where this thing comes from? – Gareth McCaughan Mar 31 at 21:38