Claiming Expenses

When entering expenses, do I calculate the percentage or does Turbotax? For example say I spent $100 on meals and entertainment. I know you can claim 50%. Do I enter $100 or $50? Do I do the math or does Turbotax? I’m worried both I do the math and Turbotax so it’s being done twice and I get credit for $25? I always do the calculations myself and enter the lower amount not the full amount.