14(8 - 5) = 42
48 - 1 - 5 = 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).
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.
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, ........