Is there a formula to automatically do the below? I have a spreadsheet with 13,000 records on it and need this done ASAP? Any help would be appreciated. Thanks. Kim G

Here's how it looks:

12345
12345
12345
12345
12456
12456
12456
12457
12457

Here's how I want it to look:

12345
12345
12345
12345

12456
12456
12456

12457
12457