Two points to clarify this story.

Firstly, the first-level tech is working on the customer’s computer hence why he is being asked to press the NUMLOCK key instead of being asked to tell the customer to press the key. Secondly, the assumption here is that the computer in question is a small laptop (and/or desktop keyboard) that doesn’t have dedicated number keys and as such must have NUMLOCK enabled to type numbers with letter keys.

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