Crystal Report in C#

1) Select Draged field (which appears as 20,000)
2) Select right click on that and select Format Embaded Field option.
3) Where u can find different options for numeric
4) Select option as per your required format..!!

right click on the field, choose format object, then select the number tab.
then click on the customize button. then unchecked the thousands Separator : Symbol : ,
check box.

You are done.

if your field is string
Within Crystal, you can do it by creating a formula[Field Explorer-> Formula Field-> right click->new Formula-> give a name] that uses the ToNumber function. It might be a good idea to code for the possibility that the field might include non-numeric data - like so:

If NumericText ({field}) then ToNumber ({field}) else 0

now follow the above steps for the formula field.