# Cannot sort numeric cells correctly

I was given a MS Excel spreadsheet to perform updates. I am using LibreOffice. Two of the columns are numeric. In each cell there is a symbol ' in front of each number. I believe this is preventing me from sorting correctly as I have removed the symbol from some cells and then I can sort correctly. I cannot remove the ' symbol from each cell as the spreadsheet has 10,000 lines. Why is this symbol ' in front of each number in the cells and is there a way for me to remove? Thank you in advance.