Manager asked me to create a spreadsheet showing tasks in a project with percentage complete to send to client.
Sounds easy, even though I prefer JIRA, I created spreadsheet with all tasks and asked each developer responsible to fill in percentage done.

But I did it completely wrong. I have to give estimate for how long it took for each task and make sure total complete is 70 percent and number of days add up to 10. WTF guess the estimate to match the total. And this is how you teach me project management.

Did I mention that all this is happening after most of the project is done?