1. ## Make 42

This should be nice and easy (although a few of my friends have struggled with it for a while) so I imagine some of you will get this almost instantly, for those that don't, stick with it for a few minutes.

Using the numbers 1, 4, 5, 8 and the operations +, -, *, / make 42 (using each number at most once).

2. 14(8 - 5) = 42

48 - 1 - 5 = 42

3. 14 is not an allowed number (nor is it 1 and 4 combined using an allowed operator... I didn't define a concatenation operator). Had I said "...using the digits 1, 4, 5, 8..." that may be a more reasonable thing to do, but I'll assure you this is a perfectly "standard" question, there is no clever trick, etc.

So give it another go.

4. Originally Posted by fov
14 is not an allowed number (nor is it 1 and 4 combined using an allowed operator... I didn't define a concatenation operator). Had I said "...using the digits 1, 4, 5, 8..." that may be a more reasonable thing to do, but I'll assure you this is a perfectly "standard" question, there is no clever trick, etc.
Ok Ok smarty pants, but remember this in future:
per James J Fixx (games for the super-intelligent):
"in a puzzle, EVERYTHING not explicitly prohibited is allowed"

Not just that; you stated:
"Using the numbers 1, 4, 5, 8 and the operations +, -, *, / ";
IF this means all 4 digits must be used, then it also means all
4 operations must be used!

I got this (but used a set of brackets):
(1/4 + 5) * 8 = 42

If that's what you want, then puzzle should be worded:
using the digits 1,4,5,8 once each and in any order,
and one or more of the operators +, -, *, /,
and as many sets of brackets as you wish, ........

5. Brackets were not mentioned, I think they are not allowed in the problem, and you can use each number AT MOST ONCE, but this does not mean you have to use all of them. If you can think of a way using only 3 of them, it is still a valid answer.