Tip 61: Working with Credit Card Numbers
If you’ve ever tried to enter a 16-digit credit card number into a cell, you may have discovered that Excel always changes the last digit to a zero. Even worse, maybe you didn’t discover the changed credit card number until it was too late.
Why does Excel change your numbers? The reason is that Excel can handle only 15 digits of numerical accuracy.
Entering credit card numbers manually
If you need to store credit card numbers in a worksheet, you have three options:
→ Precede the credit card number with an apostrophe. Excel then interprets the data as a text string rather than as a number.
→ Preformat the cell or range by using the Text number format. Select the range, choose Home⇒Number and then select Text from the Number Format drop-down control.
→ Enter the card number with dashes or spaces. Embedding a dash character (or any other non-numeric character) forces Excel to interpret...