I need to enter credit card nos (16 digits) to Excel. Will I be able to enter these nos as it is or will I have any issues?

You will be able to add the numbers however you may need to consider a few things

Firstly - ensure that decimal points and comma separators are turned off for these cells using the Format cells options others have mentioned

Secondly - If the number begins with a zero it will take the number out. In this instance you may want to format the cells as text. You will be able to use text/lookup functions with this.

The second is a better solution as a credit card number is a 'reference number' and not a 'value' therefore treating it as text will mean Excel does not attempt to treat it as a number.

I agree with Ms. Alix

Select all those cells in which you want that16 digits numbers - right click - click format cells - on the Number tab under category click Number - on right side write0 for decimal places -  click ok.

1. If you are using credit card numbers, or other number codes that contain16 digits or more, you must use a text format. That’s because Excel has a maximum of15 digitsSelect the cell or range of cells that contains the numbers that you want to format as text.

    You can also select empty cells, and then enter numbers after you format the cells as text. Those numbers will be formatted as text.

1. On the Home tab, in the Number group, click the arrow next to the Number Format box, and then click Text.

 If you don't see the Text option, use the scroll bar to scroll to the end of the list.

Format the fields (in Number Custom Format) as

you can enter16 digits number without any difficulty, however you may decimal  and comma commands to reflect in millions and can also use without separator in text format also.

You can also enter the card numbers in the format (the way it appears on credit cards). 

All you have to do is

1. select all the cells in which you want to enter the numbers/

2. right click and select FORMAT CELLS

3. select CUSTOM from the left list

4. input --->  <--- (without arrows)

5. click OK.

Now all you need to do is enter the credit card number. (you wont need to add the hyphens or dashes, the number will be formatted once you click enter...