Percents of numbers and money amounts

key notes :

Percent (%) means “per 100”

• 1% = 1 out of 100
• Example: 25% = 25/100 = 0.25 ✅

Converting between Percent, Decimal, and Fraction

Percent → Decimal: divide by 100

• Example: 40% → 0.40

Percent → Fraction: write over 100 and simplify

• Example: 50% → 50/100 = 1/2

Finding the Percent of a Number

• Formula:

Percent of a number = Percent / 100 × Number

• Example: 20% of 150 = (20 ÷ 100) × 150 = 30 🎯

Finding a Number from a Percent

• Formula:

Number = Part / Percent×100

• Example: 30 is 25% of what number?
• 30 ÷ 25 × 100 = 120 \] ✅

Finding the Percent from Part & Whole

• Formula:

Percent = Part / Whole × 100

• Example: A student scored 45 out of 60 →
• 45 ÷ 60 × 100 = 75\% \] 📈

Percents in Money Problems 💵

Discount: Subtract % of price from original price

• Example: ₹500 shirt at 10% off → 10% of 500 = 50 → 500 – 50 = ₹450 🛍️

Profit & Loss:

• Profit % = (Profit ÷ Cost Price) × 100
• Loss % = (Loss ÷ Cost Price) × 100 💹

Interest:

• Simple Interest = (Principal × Rate × Time) ÷ 100 ⏳

Tips to Solve Quickly ⚡

• Convert percent to decimal first for faster multiplication
• Always check if question is asking for percent of number, the number from percent, or percent itself
• Use estimation for checking answers

Common Words in Money Percent Problems 💡

• Discount, Sale, Profit, Loss, Interest, Tax, Tip, Commission

Visual Tip: Draw a 100-block grid to quickly visualize percentages 🟩⬜

Learn with an example

let’s practice!