When entering the Meals 50% limit: do I take 50% of the amount first and then enter into the field or do I enter the full amount of the meals and TT takes the 50%?

Example:  My total meals (50%) is actual cost of $1,000.  Do I put $1,000 into the Turbo Tax field or do I do the 50% calculation first and put $500 into Turbo Tax.