'she's fifty if she's a day'?

[Mehrgan]

Hi,
Would anyone please tell me what this could possibly mean? There was no context at all in the book and the students were asked to figure out the meaning.


Thanks a lot!

[5jj]

It means, "She is at least fifty",

The idea is that is she is a day old (or more), which she obviously is, then she must be fifty or more. The idea of her being less than fifty is as incredible as that of her being only a day old.

[Mehrgan]

Many grateful thanks!