I am entering mileage, I have an app that tracks my work mileage, Idk my beginning or ending mileage number, I only have how many miles I drove for work, what do I do?

[MaryK1]

You can enter the miles and not the odometer. 

IRS regulations and guidance provide that to qualify for the mileage deduction you are required to have a record of four facts when you drive your car for business:

• time and date of the drive
• total distance of the drive
• destination of the drive, and
• business purpose of the drive.