Discounts Multiply

Stacked discounts do not add up the way they look. "50% off, then another 50% at checkout" sounds free. It is not. The second cut works on the already-lower price, so you pay half of half: 0.50 × 0.50 = 0.25. That is 75% off, not 100%.

The rule is simple: each discount multiplies the price, it never adds to the savings. Two cuts always leave more on the tag than your gut expects.