Search numbers in single line

Hi,

I'd like to search for a numbers in a single line only e.g.
"some text, some more text
123
some text, some more text
some text, some more text
124"

etc.
For now I came up with this ([^\d]|^)\d{3}([^\d]|$) but it searches all the 3 digit numbers e.g.
if the text contains "123 items were purchased" it removes the 123 within the text, which I don't want. I only want to be able to find/remove the 3 digits in single lines, not surrounded by any other text.

Can anyone help me?

Why not ^\d{3}$

This is exactly what I wanted.
Thank you!