Javascript that calculates a percentage

[pixelduststudio]

I am working in a PDF Form and trying to do this calculation.

I understand that I need to do it in javascript, which I have never done. Any help is appreciated.

Total Services Costs x .9 = Total Services Costs 2

[try67 · Accepted solution]

You can use this code as the custom calculation script of the second field:

event.value = Number(this.getField("Total Services Costs").valueAsString) * 0.9;

[pixelduststudio]

Thank you!