Analyze·Beginner·Playground·15 min·Updated Sep 30, 2026

Find duplicate vendor payments

Scenario

Accounts payable thinks some vendors got paid twice last month.

Mission

Find the duplicate payments and total how much to reclaim.

Start Files

InvoiceNumberVendorAmountDate
INV-4001Umbrella Freight27272026-07-13
INV-4002Northwind Supplies60162026-07-07
INV-4003Umbrella Freight15852026-07-10
INV-4004Fabrikam Parts64512026-07-22
INV-4005Initech Services69172026-07-06
Preview — first 5 rows of vendor-invoices.csv

Your task

  1. Match invoices by Vendor and Amount to surface likely duplicate payments.
  2. Confirm each candidate pair has a different invoice number but a date within a few days of the other.
  3. Total the dollar amount of the duplicate (extra) payments only — not both copies.

Prompt idea:

Here is a vendor invoice export. Find invoices that look like duplicate payments — same vendor and amount, different invoice number, dates close together — and total how much we'd reclaim.

Check Your Result

What is the total dollar amount of duplicate payments found (nearest dollar)?

Need a hint?

Match on Vendor + Amount — a duplicate invoice has the same vendor and amount but a different invoice number a few days later.

Reveal Solution

The solution files contain the completed challenge. Review the approach to see if you missed any edge cases.

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