Скачать или смотреть Here are some easy and fast percentage tricks — great for mental math, exams, or daily calculations

Here are some easy and fast percentage tricks — great for mental math, exams, or daily calculations 👇


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🧮 Basic Shortcuts

1. Find 10%, 5%, 1% quickly

10% = move decimal one place left
👉 10% of 250 = 25

1% = move decimal two places left
👉 1% of 250 = 2.5

5% = half of 10%
👉 5% of 250 = half of 25 = 12.5



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🧠 Reversal Trick

x% of y = y% of x 👉 25% of 60 = 60% of 25 = 15


This is super useful for big/small numbers!


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💰 Increase / Decrease by a Percentage

Increase:

To increase by 20%, multiply by 1.2
👉 500 × 1.2 = 600

Decrease:

To decrease by 20%, multiply by 0.8
👉 500 × 0.8 = 400


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⚡ Finding Percentages Quickly

2. Multiples of 10%

You can add or subtract easily:

20% of 250 = 10% + 10% = 25 + 25 = 50

30% of 250 = 25 + 25 + 25 = 75

15% of 200 = 10% + 5% = 20 + 10 = 30

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🔢 Fraction–Percentage Equivalents

Fraction Percentage

1/2 50%
1/3 33.33%
1/4 25%
1/5 20%
1/8 12.5%
3/4 75%



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🧩 Percent Change Formula

\text{Percent Change} = \frac{\text{New – Old}}{\text{Old}} \times 100

= (100 − 80)/80 × 100 = 25% increase


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🔥 Quick Tip for Discounts

Two successive discounts don’t add directly — use:

\text{Net discount} = A + B - \frac{AB}{100}

= 20 + 10 − (20×10)/100 = 28%


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Would you like me to make this into a visual cheat sheet (PDF) for quick reference?