🔵Fractions as Decimals
A decimal is another way to write a fraction. A decimal point separates the whole number part from the fractional part.
- Tenths place: first digit after decimal = denominator 10 (e.g. 3/10 = 0.3)
- Hundredths place: second digit after decimal = denominator 100 (e.g. 25/100 = 0.25)
Think of it like Indian currency: Rs.1 = 100 paise. 10 paise = 10/100 = 0.10. 1 paisa = 1/100 = 0.01.
Converting fractions to decimals: Make the denominator 10 or 100, then write in decimal form. Adding a zero to the right of a decimal does NOT change its value: 0.3 = 0.30.
👀 See a worked example
🤖 Vidi's Key Points
- Tenths: first place after decimal point, denominator 10
- Hundredths: second place after decimal point, denominator 100
- To convert fraction to decimal: make denominator 10 or 100
- Adding zeros to the right of a decimal does NOT change its value: 0.3 = 0.30
🟢Compare Decimals
Comparing decimals: line up the decimal points and compare digit by digit from left to right.
Steps:
- Line up the decimal points (add zeros if needed)
- Compare the ones place first
- If same, compare tenths
- If same, compare hundredths
- The first place where digits differ decides which is larger
Important: 0.3 = 0.30 (adding a zero on the right does not change the value, it just allows comparison).
👀 See a worked example
🤖 Vidi's Key Points
- Always line up decimal points before comparing
- Compare left to right: ones, tenths, hundredths
- Add zeros to the right when needed for comparison — value stays the same
- In real-life problems, read carefully — smaller time = faster!
🟣Add and Subtract Decimals
The most important rule for adding/subtracting decimals: ALWAYS line up the decimal points!
Column Method Steps:
- Write numbers with decimal points aligned
- Add zeros to make same number of decimal places
- Add or subtract from RIGHT to LEFT (like whole numbers)
- Bring the decimal point STRAIGHT DOWN into the answer
- Carry or borrow just like with whole numbers
👀 See a worked example
🤖 Vidi's Key Points
- ALWAYS line up decimal points — this is the most important rule
- Add zeros to make all decimals have the same number of places
- Carry and borrow exactly as you would with whole numbers
- Bring the decimal point straight down into the answer
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