Percentage Change Simulation

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LIVE

Original 80New 100Change +20+25% increase

Learning mode

Transform a quantity

Context

Original value80

New value100

Known rate15%

Speed1×

View & focus

Zoom100%

Drag to pan. Tap the original tank, new tank, difference bridge, or percentage ring.

FocusPercentage ring

Value25%

Before and after

Rules & formulas

percentage change = (new − original) ÷ original × 100%
change amount = original × rate ÷ 100
new after increase = original × (1 + rate ÷ 100)
new after decrease = original × (1 − rate ÷ 100)

Learning outcomes

Identify original, new, and actual change.
Calculate percentage increase or decrease.
Explain why the original is the denominator.
Apply a known percentage rate.
Distinguish percent change from percentage points.

Try: Change 120 to 90, then apply a 15% increase to 200.

Seven-question challenge

Guided visual narration

Language

Narrator

Volume boost150%

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Narration uses embedded audio routed through the page audio output, so it can be captured when the browser tab is recorded with tab audio. No microphone is used.

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