Excel - formatting cells

I designed a Visual Basic form from within excel to input currency values onto a spreadsheet. The cells on the spreadsheet have been formatted to 'currency', but when I type in a value on the form thats only a number (without the dollar sign) it only inputs a number on the spreadsheet even though the spreadsheet cell is formatted for currency. Why does this happen?, is there a way to make the VB form input boxes automatically convert a normal number to currency?