50 percent off 85

50% off 85 is 42.5

85 minus 50 percent off is 42.5

The discount itself is 42.5: 85 × 50 ÷ 100 = 42.5. Taking it off 85 leaves 42.5.

Only approximately: 42.5 ÷ 0.5 = 85. The discount is rounded to the cent, so several prices give the same 42.5 — 85 (discount 42.5) and 85.01 (discount 42.51); the paid price alone cannot tell them apart.