A percentage is just a fraction wearing a costume — always out of 100. Click through the tabs to explore every idea from the chapter: converting, comparing, growing, discounting, and the sneaky traps percentages can set.
A percentage is a fraction with denominator 100. Type any fraction (a/b) and watch it convert instantly, with a bar model showing the equivalence.
Finding y% of a value s means multiplying: (y/100) × s. Try Madhu & Madhav's sugar problem with your own numbers.
20% is always double 10%. 25% = 20% + 5%. Pick a value and watch the whole family of percentages fall out mentally.
Like the millet-and-water kanji example: a ratio's parts can be turned into percentages of the whole mixture.
If sales exceed the target, the percentage crosses 100%! Enter a value and its target to see where it lands on the number line.
Comparing raw scores out of different totals can mislead. Converting to percentages puts everything on the same 100-point scale.
Change is always measured against the original amount: (amount of change ÷ original) × 100.
Profit % is always calculated with respect to the Cost Price (what you paid), never the Selling Price.
Without compounding, interest is always earned on the same principal (linear growth: p(1+rt)). With compounding, interest earns interest too (exponential growth: p(1+r)ᵗ).
Does a 30% discount + 20% discount equal a 50% discount? Not quite — successive percentages compound, they don't add!
Test what you've learned across all ten stations.