---
title: "Checksums"
slug: "checksums"
updated: 2026-08-10T20:20:46Z
published: 2026-08-10T20:20:46Z
canonical: "help.idibilling.com/checksums"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.idibilling.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Checksums

- **Public Function CheckDigit_IBM_Mod10(strNum As String) As String**

Calculates the checksum of the string and returns the result. For example, if CustomerAcctNumber is 1003, the expression **CheckDigit_IBM_Mod10(CustomerAcctNumber)** returns “3”.
- **Public Function AppendCheckDigit_IBM_Mod10(strNum As String) As String**

Calculates the checksum of the string and returns the original string with the checksum appended. This function enables the use of nested expressions. For example, if the CustomerAcctNumber was 1003 and the TotalAmountDue was 504.22, the expression **=AppendCheckDigit_IBM_Mod10(AppendCheckDigit_IBM_Mod10([CustomerAcctNumber])** **&""& AppendCheckDigit_IBM_Mod10([TotalAmountDue]))** returns “10033 504.2253”.