The Question is;
Evaulate: 102x42x103 104x4
The answer is 40, apparently. But I have no idea how to get to it or what this has to do with indices?
These are two numbers: 102x42x103 and 104x4. I am assuming "x" means multiplication, but it is not clear what operator is between these numbers.
An index (usually) is just an ordinal number (such as "first," "second," etc.). You probably need to give us more context to the question.
That is all there is, it is question 27 on the British Army Technical Selection Test sample.
Technical Selection Test - British Army Website
Hmm, I agree, this is puzzling. In fact, the next question, titled "Precedence," says, "Compute the following: 8-6(4+3)2." The options are -17, -2, 1, 2 and 7, and the correct one is apparently -17. WolframAlpha disagrees.