What is Multiplying a Decimal by 10?

S1-SA2-0276

Grade Level:

Class 5

Maths, Finance, Computing, AI

Definition

What is it?

Multiplying a decimal by 10 means making the decimal number ten times bigger. When you multiply a decimal by 10, the decimal point moves one place to the right, making the number larger.

Simple Example

Quick Example

Imagine a small packet of biscuits costs ₹5.50. If you buy 10 such packets for your friends, how much would it cost? It would be ₹5.50 multiplied by 10, which is ₹55.00.

Worked Example

Step-by-Step

Let's multiply 3.45 by 10.

Step 1: Write down the decimal number: 3.45
---Step 2: Identify the decimal point. It is between 3 and 4.
---Step 3: To multiply by 10, move the decimal point one place to the right.
---Step 4: The decimal point moves from between 3 and 4 to between 4 and 5.
---Step 5: The new number becomes 34.5
---Step 6: So, 3.45 x 10 = 34.5

Answer: 34.5

Why It Matters

Understanding this helps you handle money faster, like calculating costs for 10 items. In finance, bankers and investors use this to quickly scale up numbers. Even computer programmers use similar logic for calculations, laying the groundwork for careers in AI and data science.

Common Mistakes

MISTAKE: Moving the decimal point to the left instead of the right. E.g., 2.3 x 10 = 0.23 | CORRECTION: Remember, multiplying makes a number bigger, so the decimal point moves right. 2.3 x 10 = 23.

MISTAKE: Forgetting to add a zero if there are no more digits to move the decimal past. E.g., 7.2 x 10 = 7.20 | CORRECTION: If you move the decimal past the last digit, add a zero as a placeholder. 7.2 x 10 = 72.0 or just 72.

MISTAKE: Thinking you need to do long multiplication. E.g., doing full multiplication for 4.8 x 10 | CORRECTION: For multiplying by 10, 100, or 1000, there's a shortcut! Just move the decimal point.

Practice Questions

Try It Yourself

QUESTION: A small bottle of juice costs ₹12.75. How much would 10 such bottles cost? | ANSWER: ₹127.50

QUESTION: What is 0.8 x 10? | ANSWER: 8

QUESTION: If a car travels 65.3 km in one hour, how much distance would it cover if it could maintain that speed for 10 hours? | ANSWER: 653 km

MCQ

Quick Quiz

What is the result of 9.05 multiplied by 10?

0.905

90.5

9.05

905

The Correct Answer Is:

Multiplying by 10 means moving the decimal point one place to the right. So, 9.05 becomes 90.5. Options A and D move the decimal point incorrectly, and option C just adds a zero without changing the value.

Real World Connection

In the Real World

When calculating the total cost of 10 items in a shop, like 10 packets of chips, the shopkeeper or the UPI app uses this concept. Or, if a cricketer scores 7.5 runs per over, multiplying by 10 quickly tells you they'd score 75 runs in 10 overs at that rate.

Key Vocabulary

Key Terms

DECIMAL: A number that includes a decimal point, like 3.14 | DECIMAL POINT: The dot that separates the whole number part from the fractional part | PLACE VALUE: The value of a digit based on its position in a number | MULTIPLICATION: The process of finding the product of two or more numbers

What's Next

What to Learn Next

Great job learning about multiplying decimals by 10! Next, you should learn about multiplying decimals by 100 and 1000. It uses the same easy trick, just moving the decimal point more times!