I'm always looking for ways to save money, and I've developed some discount calculation tricks that really help. My favorite is the "double discount" trick - when something is 30% off, then an additional 20% off, it's not 50% off total. You multiply the discounts: 0.7 × 0.8 = 0.56, so it's actually 44% off.
I also use estimation techniques for quick comparisons. If something is $47 with 25% off, I round to $50, take 1/4 off ($12.50), so about $37.50, then adjust down a bit since I rounded up.
What discount calculation tricks or estimation techniques do you use when shopping?
The double discount trick is essential! I teach my students that discount calculation tricks like this can save them money. Another one: when something is 30% off then take an extra $10 off," do the percentage first. $100 item, 30% off = $70, then minus $10 = $60. That's 40% off total, not "30% plus $10."
For grocery discount calculation tricks, I watch for 10 for $10" deals. Even if I only need 3, each is $1. But sometimes it's actually cheaper to buy individual! Like if they're normally $1.19 each, 10 for $10 is a deal. But if they're normally $0.89 each, 10 for $10 is worse. These estimation techniques require quick math.
When cooking, I use discount calculation tricks for recipe scaling. If a recipe serves 4 and I'm making it for 6, that's 1.5 times. Instead of exact math, I use estimation techniques: take the 4-serving amounts, add half again. So 2 cups becomes 3 cups, 1 teaspoon becomes 1.5 teaspoons. Close enough for cooking!
For travel booking, I use discount calculation tricks with flight prices. If a flight is $300 but has a $50 discount code, that's about 17% off. But if there's also a 10% cashback offer, that's additional savings. These estimation techniques help me compare different booking options quickly.