Excel file is too big compared to few data it contains

Dear Experts

I have excel table which contains just few rows and columns of data. Originally table was big with many sheets and lot of data, but before I receive it, sender removed all sheets and left only single sheet with one summary table.

Problem - excel file is BIG - 24 MB.

I tried simply thing, created new sheet, empty one and DELETED the original one with summary table, saved and ...... size is the same.

So now, I have excel file which seems to be very empty, just having 24 MB.

Can you advice where is problem and how to shring size down to something reasonable?

Thanks

Vladimir