Addition and Subtraction (3-digit) — Lesson
🌟 Let's Go on a Number Adventure! 🌟
Imagine you are at a big Indian fair 🎡 in your city. You have 235 rupees in your pocket. You buy a yummy jalebi for 128 rupees. How much money do you have left? 🤔
Or, if your friend gives you 146 marbles and you already have 312, how many marbles do you have now? Let's learn how to add and subtract these big numbers easily! 🎉
➕ Core Concepts: Adding and Subtracting 3-Digit Numbers
When we add or subtract numbers like 3-digit numbers (numbers from 100 to 999), we need to remember to line up the digits properly:
| Hundreds (H) | Tens (T) | Ones (O) |
|---|---|---|
| 3 | 1 | 5 |
Let's add 312 and 146 step by step:
| H | T | O |
|---|---|---|
| 3 | 1 | 2 |
| 1 | 4 | 6 |
| 4 | 5 | 8 |
So, 312 + 146 = 458! 🎉
Now, let's subtract 128 from 235:
| H | T | O |
|---|---|---|
| 2 | 3 | 5 |
| 1 | 2 | 8 |
| 1 | 0 | 7 |
So, 235 - 128 = 107. You have ₹107 left after buying jalebi! 😋
📚 Key Formulas / Rules
- Addition: Always add digits starting from the ones place → tens → hundreds.
- Subtraction: Always subtract digits starting from the ones place → tens → hundreds.
- Carry Over: If sum of digits is more than 9, carry over the extra to the next place.
- Borrowing: If top digit is smaller than bottom digit in subtraction, borrow 1 from the next higher place.
🤓 Did You Know?
The ancient Indians were great mathematicians! They invented the number zero (0) and the decimal system, which helps us do addition and subtraction easily today. Without zero, adding big numbers would be much harder! 🇮🇳✨
📝 Exam Tips
- Always write numbers in a neat column: hundreds, tens, ones.
- Check if you need to carry or borrow before adding or subtracting.
- Double-check your answer by doing the reverse operation (e.g., check subtraction by adding).
- Board exams often ask simple addition or subtraction questions with 3-digit numbers.
- Be careful not to mix up place values — that can change your answer!
Keep practicing and have fun with numbers! 🎉📚
Addition and Subtraction (3-digit) — Mcq
Addition and Subtraction (3-digit) — Mnemonic
🌟 Fun Mnemonics for Addition & Subtraction (3-digit) 🌟
-
1. The Carry and Borrow Dance 💃🕺
“Carry up, Borrow down,
Digits move, no need to frown!”When adding, if numbers are big, carry the extra to the next place.
When subtracting, if top is small, borrow from the next place.Remember: Carry UP, Borrow DOWN! Easy, right? 😊
-
2. ABC of Addition 🅰️🅱️🅲️
A = Add digits from right,
B = Bring carry forward,
C = Continue till left!Think: A-B-C = Add, Bring, Continue.
Like climbing stairs, step by step! 🪜 -
3. Hindi Rhyming Trick for Subtraction 🐘
"ऊपर वाला छोटा, तो नीचे से माँगना।
नहीं तो काम नहीं बनेगा, ध्यान से समझना।"(If the top digit is small, borrow from below.
Otherwise, the work won’t go, so understand well!)Borrowing is like asking your friend for a little help! 🤝
Try these mnemonics next time you add or subtract 3-digit numbers! 🎉
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