Tip one: memorise the basic fractions. ¼ = 25%, ⅓ ≈ 33.3%, ½ = 50%, and ¾ = 75%. This shortcut saves you from pulling out your phone every time you split a dinner bill. Tip two: if you’re converting a decimal like 0.07, just move the decimal point two spots to the right—it becomes 7%. No calculator needed.
For the reverse—finding what a number is as a percentage of another—use the same divide-and-multiply formula. Got 15 out of 60? 15 ÷ 60 = 0.25, times 100 is 25%. It’s like a mental yoga stretch for your brain.
If you’re stuck, remember this rhyme: “Divide the part by the whole, then multiply by 100 to reach the goal.” Corny? Yes. Effective? Absolutely.
When Percentages Get Playful: Increases and Decreases
Sometimes you need to find a percentage change. Say your rent went from $1,200 to $1,320. Subtract the old from the new, divide by the old, and multiply by 100: (120 ÷ 1,200) × 100 = 10% increase. Ouch, but at least you can articulate the pain.
Discounts work the same way: if that jacket now costs $56 instead of $80, the decrease is (24 ÷ 80) × 100 = 30% off. Exactly what the tag promised. It’s a satisfying moment of verification.
Percentage points are different from percentages, by the way. If a politician says “support grew by 5 percentage points,” they mean from 40% to 45%, not a 5% increase. This is how you win arguments at brunch.
