What is Multiplying by Four?

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Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Multiplying by four means adding a number to itself four times. It's a quick way to find the total when you have four equal groups of something. Think of it as finding the total of four identical sets.

Simple Example

Quick Example

Imagine you buy 4 packets of biscuits. If each packet costs 10 rupees, how much do you pay in total? Instead of adding 10 + 10 + 10 + 10, you can simply multiply 10 by 4 to get 40 rupees.

Worked Example

Step-by-Step

Let's find out what 7 multiplied by 4 is.

1. Understand the problem: We need to find the total when we have 4 groups of 7.
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2. Think of it as repeated addition: This means 7 + 7 + 7 + 7.
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3. First addition: 7 + 7 = 14.
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4. Second addition: Now add the next 7 to the sum: 14 + 7 = 21.
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5. Third addition: Add the last 7 to the sum: 21 + 7 = 28.
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6. Alternatively, use multiplication: We know that 7 multiplied by 4 is 28.
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Answer: 7 multiplied by 4 is 28.

Why It Matters

Understanding multiplication by four helps you quickly solve problems in daily life and in higher math. It's crucial for careers like finance, engineering, and even managing a small business, where calculating totals and quantities efficiently is key.

Common Mistakes

MISTAKE: Adding the number four times instead of multiplying by four. For example, for 5 x 4, doing 5 + 5 + 5 + 5 + 5 (five times) instead of 5 + 5 + 5 + 5 (four times). | CORRECTION: Remember that 'multiplying by four' means you are adding the *original number* to itself *four times*, not adding four to the number four times.

MISTAKE: Confusing multiplication by four with adding four. For example, for 6 x 4, writing 6 + 4 = 10. | CORRECTION: Multiplication is repeated addition. 6 x 4 means 6 + 6 + 6 + 6, not 6 + 4.

MISTAKE: Forgetting basic multiplication facts involving four, leading to slow calculations. For example, taking a long time to figure out 4 x 8. | CORRECTION: Practice your multiplication tables for four regularly. Knowing them by heart makes calculations much faster and easier.

Practice Questions

Try It Yourself

QUESTION: A auto-rickshaw charges 5 rupees per kilometer. How much will it cost for a 4-kilometer ride? | ANSWER: 20 rupees (5 x 4 = 20)

QUESTION: If one cricket team has 11 players, how many players are there in 4 such teams? | ANSWER: 44 players (11 x 4 = 44)

QUESTION: A street vendor sells 4 samosas for 20 rupees. If you want to buy 4 such sets of samosas, how much will it cost you? (Hint: First find the cost of one samosa, then the total.) | ANSWER: 80 rupees (One set costs 20 rupees. So, 20 x 4 = 80 rupees)

MCQ

Quick Quiz

Which of these is the correct way to calculate 9 multiplied by 4?

9 + 4

9 x 9 x 9 x 9

9 + 9 + 9 + 9

4 + 4 + 4 + 4 + 4 + 4 + 4 + 4 + 4

The Correct Answer Is:

Multiplying by four means adding the number (in this case, 9) to itself four times. Option C, 9 + 9 + 9 + 9, correctly represents this repeated addition. Options A and B are incorrect operations, and Option D is adding 4 nine times, which is also 36, but not the direct definition of 9 multiplied by 4.

Real World Connection

In the Real World

In India, when you calculate your monthly mobile data usage, if you use 4 GB every week, you multiply 4 GB by 4 weeks to estimate 16 GB for the month. Or, if a carpenter needs 4 pieces of wood, each 3 meters long, they'll multiply 3 x 4 to know they need 12 meters of wood in total.

Key Vocabulary

Key Terms

MULTIPLY: To combine numbers to get a product | PRODUCT: The result of multiplication | REPEATED ADDITION: Adding the same number multiple times | FACTOR: A number that is multiplied by another number to find a product

What's Next

What to Learn Next

Great job understanding multiplication by four! Next, you can explore 'What is Multiplying by Five?' and then move on to other multiplication tables. This will build your foundation for larger multiplication problems and division.