Mental Percentage Calculation Trick
📌 The core trick involves leveraging the fact that "percent" means dividing by 100, which can be done at any stage of the calculation.
🔢 To calculate $X\%$ of $Y$, divide by 100 either by dividing $X$ by 100, or by dividing both $X$ and $Y$ by 10 sequentially ($10 \times 10 = 100$).
💡 Example: $61\%$ of $80$ is calculated by $(61 \div 10) \times (80 \div 10) = 6.1 \times 8 = 48.8$.

Application Examples
🔢 For $3\%$ of $400$, the easiest method is to divide $400$ by $100$ first, resulting in $3 \times 4 = 12$.
🔢 For $80\%$ of $70$, divide both by $10$: $8 \times 7 = 56$.
🔢 For $24\%$ of $60$, divide both by $10$: $2.4 \times 6 = 14.4$.
🔢 For $133\%$ of $1,200$, divide $1,200$ by $100$ to get $13 \times 12 = 156$.

Key Points & Insights
➡️ Manipulate the division by 100 by splitting it into two sequential divisions by 10 to simplify complex numbers before multiplication.
➡️ Prioritize dividing numbers that result in simpler integers or easier decimals first (e.g., dividing by 100 when dealing with multiples of 100).
➡️ Mastering this technique allows for rapid mental calculation of percentages, often within seconds.

📸 Video summarized with SummaryTube.com on Oct 10, 2025, 17:57 UTC