Ok, seems simple, but this is really doing my head in

Cut and pasted (from web browser) a table of figures and put in Excel.

Re-formatted the worksheet, cleared all previous formatting, and put into a sensible shape.

Trying to add up a column, and it won't recognise the numbers in the column ie that they are in there; Excel seems to think the cell is empty. If I manually over-type the same number it recognises this, and add's it to the total.

I've tried to copy out the numbers, put into word, clear formatting and paste back in - same problem.

Any ideas how I can get Excel to recognise the cells as having a number in them?

Here's a selection of data from spreadsheet.

26/02/2013 VIS LV INSUREFRIZZEL 336.77

26/02/2013 VIS INT'L 0078260494 35.40

26/02/2013 VIS INT'L 0078260493 37.58

26/02/2013 VIS INT'L 0078260495 40.75