Dividing by 2 numbers at once, what is the answer? Let's say i have 4/1/5. or 4 divided by 1 divided by 5. Are there any rules that i am allowed to use to stop any mistakes?, for example this has 2 solutions, 4/5 , and 20.

Edit: Thanks for your responses. It seems the rule of thumb is to start from the beginning and follow through the numbers, while any brackets should be dealt with beforehand.

In which case something like 1/2/3/4 is in fact 1/24. 

Edit2: There's a small bounty for whoever can prove that there solution is always the case, and any misuse of it always fails
In the USA and Canada, perhaps other places too, we use the BEDMAS system for interpreting expressions. First, we calculate the result of bracketed sub-expressions. Then exponentiation. Then from left to right, resolving divisions or multiplications as they show up. Then from left to right, resolving additions and subtractions as they show up. 

So in the BEDMAS convention, we would deal with your 4/1/5 by doing the divisions left-to-right. 4/5.

Edit:

As the comments point out, some use PEDMAS instead. P for parenthesis instead of brackets ;)
YouTube: The Order of Operations is Wrong

Take 8-2+1 for example. In reality, it actually equals (8/1)+(-2/1)+(1/1).

Applying the same logic to 4/1/5 you get:

 (4/1)/(1/1)/(5/1)
=(4/1)x(1/1)x(1/5)
=(4x1x1)/(1x1x5)
=4/5


With (P|B)EDMAS, 6/3/3 could be:

 6/(3/3)
=6/1
=6


or

 (6/3)/3
=2/3


whereas 6/3/3 actually equals

 (6/1)/(3/1)/(3/1)
=(6/1)x(1/3)x(1/3)
=(6x1x1)/(1x3x3)
=6/9
=2/3