Stop reaching for your calculator. Your brain can do this.
We've all been there: splitting a restaurant bill, calculating a discount, or figuring out a tip. Everyone pulls out their phone.
But what if you could do it faster in your head?
Calculate a 15% tip instantly (no phone needed)
10% + half of 10% = 15%
Try it: $60 bill → 10% = $6 → Half = $3 → Tip = $9 ✓
Turn hard percentages into easy ones
a% of b = b% of a
They're mathematically identical. So flip to the easier one!
❌ Hard way: 0.18 × 50 = ???
✓ Flip it: 50% of 18
50% of 18 = Half of 18 = 9
More examples:
• 4% of 75 → Flip: 75% of 4 = 3
• 25% of 88 → Flip: 88% of 25 = 22 - 3 = 22 (close enough!)
This looks like magic (but it's just math)
First digit × (First digit + 1), then add "25"
Try these:
• 35² → 3 × 4 = 12 → 1,225
• 85² → 8 × 9 = 72 → 7,225
• 25² → 2 × 3 = 6 → 625
You just learned 3 tricks. But there are dozens more—from Vedic Math to Russian multiplication techniques.
The question is: Where do you learn them? And how do you practice until they stick?
From fundamentals to advanced Vedic techniques
Practice drills to make tricks second nature
Level up from novice to expert across 11 levels
Tips, percentages, discounts—math you'll actually use
Stop Using a Calculator. Become One.
Visit app.ithopu.com to start your mental math journey today!