Addition and Subtraction (3-digit) — Lesson
🌟 Let's Explore Addition and Subtraction of 3-Digit Numbers! 🌟
1) Hook: The Great Indian Festival Shopping 🛍️🎉
It’s Diwali time! Riya went to the market with ₹345 in her wallet. She bought sweets for ₹128 and diyas (lamps) for ₹95. How much money did she spend? How much money is left with her?
Let’s help Riya by adding and subtracting these 3-digit numbers!
2) Core Concepts: Addition and Subtraction of 3-Digit Numbers
Addition: When we add, we put numbers together to find the total.
Subtraction: When we subtract, we find out how much is left or how much less one number is than another.
Addition Example:
Riya bought sweets for ₹128 and diyas for ₹95. How much did she spend in total?
| 1 2 8 |
| + 9 5 |
| 2 2 3 |
So, ₹128 + ₹95 = ₹223
Subtraction Example:
Riya had ₹345. She spent ₹223. How much money is left?
| 3 4 5 |
| - 2 2 3 |
| 1 2 2 |
So, ₹345 - ₹223 = ₹122
3) Key Formulas / Rules
Add digits column-wise from right to left (ones → tens → hundreds). Carry over if sum > 9.
Subtraction Rule:
Subtract digits column-wise from right to left. Borrow if top digit is smaller than bottom digit.
4) Did You Know? 🤔
In India, the first number system was developed thousands of years ago! The Hindu-Arabic numeral system (which we use today) was invented here and spread all over the world. So, every time you add or subtract, you’re using a system created right here in India! 🇮🇳
5) Exam Tips ✔️
- Always align digits properly: Ones under ones, tens under tens, hundreds under hundreds.
- Check your carry and borrow carefully: Forgetting to carry or borrow is a common mistake.
- Write neat numbers: It helps avoid confusion during addition or subtraction.
- Practice word problems: Many exam questions ask you to add or subtract in real-life situations.
- Board Exam Pattern: Questions may include adding or subtracting two 3-digit numbers and simple story sums.
Addition and Subtraction (3-digit) — Mcq
Addition and Subtraction (3-digit) — Mnemonic
🌟 Fun Mnemonics for 3-Digit Addition & Subtraction! 🌟
-
1. "Carry 🐘, Borrow 🐒, Maths is Fun!"
When you add and digits go over 9,
Carry the 🐘 to the next place, be bright!
If you need to subtract but the top is small,
Borrow the 🐒 from left, and stand tall! -
2. "H T O, Count Like a Pro! 🇮🇳"
Hundreds, Tens, and Ones in line,
Add or subtract, it’s really fine!
Start from Ones, move left with care,
Like counting laddus in a fair! 🍬🍬🍬 -
3. Hindi Rhyming Trick: "तीन अंकों का खेल, जोड़-घटाव में मेल!" 🇮🇳
सैकड़ों, दसों, और इकाइयों का मेल,
जोड़ो, घटाओ, बढ़ाओ खेल!
अगर जोड़ में हो कैरी की ज़रूरत,
बाएं से ले आओ, न हो कोई कसर!
घटाव में अगर ऊपर छोटा लगे,
बाएं से बोर्रो करो, डरना मत रे! 😊
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