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What is Multiplying by Two (Doubling)?
Grade Level:
Class 2
Maths, Computing, AI, Biology (cell division)
Definition
What is it?
Multiplying by two, also known as doubling, means finding a number that is twice the original number. It's like having the same amount of something again and adding it to the original amount.
Simple Example
Quick Example
Imagine you have 3 ladoos. If you multiply your ladoos by two, it means you get 3 more ladoos. So, you started with 3, and now you have 3 + 3, which makes a total of 6 ladoos.
Worked Example
Step-by-Step
Let's say your friend scored 5 runs in a cricket match, and you scored double his runs.
---Step 1: Understand the original number. Your friend scored 5 runs.
---Step 2: Understand 'double'. Double means multiplying by two.
---Step 3: Write the multiplication problem: 5 x 2.
---Step 4: Think of it as adding the number to itself: 5 + 5.
---Step 5: Calculate the sum: 5 + 5 = 10.
---Answer: You scored 10 runs.
Why It Matters
Doubling is a basic but powerful idea! In computing, it helps understand how data storage grows or how many tasks a computer can do. In biology, cell division often involves cells doubling. This skill is useful for careers in science, technology, and even managing money.
Common Mistakes
MISTAKE: Adding 2 to the number instead of adding the number to itself. For example, for 'double 5', writing 5 + 2 = 7. | CORRECTION: Doubling means adding the number to itself (5 + 5 = 10) or multiplying by 2 (5 x 2 = 10), not adding 2.
MISTAKE: Confusing doubling with 'half'. For example, for 'double 8', saying 4. | CORRECTION: Doubling makes a number bigger, specifically twice as big. Halving makes it smaller. Double 8 is 16.
MISTAKE: Thinking doubling only applies to even numbers. For example, thinking you can't double 7. | CORRECTION: You can double any number, whether it's even or odd. Double 7 is 7 + 7 = 14.
Practice Questions
Try It Yourself
QUESTION: Your mom gave you 4 rupees. Your dad gave you double that amount. How many rupees did your dad give you? | ANSWER: 8 rupees
QUESTION: A small plant grew 6 cm last month. This month, it grew double that amount. How many cm did it grow this month? | ANSWER: 12 cm
QUESTION: You have 9 stickers. Your friend has double the number of stickers you have, plus 3 more. How many stickers does your friend have? | ANSWER: 21 stickers
MCQ
Quick Quiz
What is the result of doubling the number 7?
9
14
3.5
72
The Correct Answer Is:
B
Doubling 7 means 7 + 7 or 7 x 2, which equals 14. Options A and D are incorrect calculations, and C is halving, not doubling.
Real World Connection
In the Real World
When you buy groceries online using apps like Zepto or Swiggy Instamart, sometimes they have offers like 'buy one, get one free' or 'double your loyalty points'. This uses the idea of doubling! Also, in banking, if your money grows at a certain rate, you might want to calculate how long it takes to 'double' your investment.
Key Vocabulary
Key Terms
DOUBLE: To multiply by two, or add a number to itself. | MULTIPLY: To increase a number by a certain factor. | TWICE: Two times the amount or quantity. | SUM: The result of adding numbers together.
What's Next
What to Learn Next
Great job understanding doubling! Next, you can explore 'Multiplying by Ten' and 'Multiplying by Zero'. These concepts build on your understanding of multiplication and will make you even better at quick calculations.
