Auto apply a style to a number

Hi,

Is there anyway to automatically set the style to 'input' when I enter a number. The only time I enter a number into a cell it is an input but I can't figure out how to get Excel to automatically format it once entered.

Thanks

Perfect thanks, does this require a lot of processing power? i.e. is it scanning the whole sheet everytime I add a cell, or is it just checking the new cell?