1. Count incomplete billing records
| Customer | Plan | MRR | Signup Date | Churn Date |
| Alice | Pro | 99 | 2024-01-15 | |
| Bob | Basic | 29 | 2024-02-01 | 2025-06-30 |
| Charlie | Pro | 99 | 2024-01-20 | |
| Diana | Enterprise | 299 | 2023-11-10 | |
| Emma | Basic | 29 | 2024-03-05 | 2025-08-15 |
| Frank | Pro | 99 | 2024-04-01 | |
| Grace | Basic | 2024-05-10 | ||
| Henry | Pro | 99 | 2024-06-15 | 2025-09-01 |
=COUNTBLANK(C2:C9)Result: 1
The MRR column (C2:C9) contains 8 cells, but only Grace's row (C8) is empty. COUNTBLANK returns 1, flagging that one billing rate is missing and needs to be completed before processing payment.