**RHemery**Hi there

On my form: https://form.jotform.com/62283840016956 we are processing payments via PayPal.

Is there a way to validate the vouchers £ field so it will only go through to the gateway if the sum ends in a 0 or 5?

Thanks

Rich

- JotForm Support
**Kevin_G**You may try with this, adding a Form Calculation widget to your form and then adding this formula:

Then when a number is entered it will give a result, you should validate that this number is not a decimal, if the quantity ends in 0 or 5 then the result of the calculation should be a non-decimal value, this will be achieved with conditions, this is the condition that you should use:

You should use the same condition and instead of showing a text like I'm doing you may show the payment field.

Here is my cloned form of your where I did apply this: https://www.jotformpro.com/form/62363430552955

Hope this helps.

**RHemery**This works OK but what I need is it to validate the 'I want...' field not the 'Number' field you've created... is this possible?

I guess if it's not the 'Number' field could act as a confirmation field, a bit like when you have to input your email address twice when registering for something.

I guess it's also possible to hide the 'Calculation' field?

Thanks

- JotForm Support
**Kevin_G**Yes, it can be the payment field, I used the other field only as a test, but I have removed it and I'm using the payment field and it works the same:

You can also check my form again and you should notice the change: https://www.jotformpro.com/form/62363430552955