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What is Multiplying a Decimal by 100?
Grade Level:
Class 5
Maths, Finance, Computing, AI
Definition
What is it?
Multiplying a decimal by 100 means making the number 100 times bigger. When you multiply a decimal by 100, the decimal point moves two places to the right. This makes the number larger, as you are essentially combining 100 copies of that decimal value.
Simple Example
Quick Example
Imagine a small packet of chai powder costs Rs 0.75. If you want to buy 100 such packets for a big family event, how much would it cost? You would multiply Rs 0.75 by 100. The decimal point in 0.75 moves two places to the right, making it Rs 75.00.
Worked Example
Step-by-Step
Let's multiply 3.456 by 100.
1. Identify the decimal number: 3.456
2. Identify the multiplier: 100
3. Remember that multiplying by 100 moves the decimal point two places to the right.
4. Start with 3.456
5. Move the decimal point one place to the right: 34.56
6. Move the decimal point a second place to the right: 345.6
7. The decimal point is now after the 5.
Answer: 3.456 multiplied by 100 is 345.6
Why It Matters
Understanding this helps in everyday calculations and is crucial for careers in finance, computing, and even AI. Financial analysts use it to convert small currency units to larger ones, while programmers use it in data scaling. It's a fundamental skill for anyone working with numbers.
Common Mistakes
MISTAKE: Moving the decimal point to the left instead of the right. Students might think multiplying makes the number smaller. | CORRECTION: Multiplying by 100 always makes the number larger. So, the decimal point must move to the RIGHT.
MISTAKE: Moving the decimal point only one place, or more than two places. Students might confuse it with multiplying by 10 or 1000. | CORRECTION: The 'two zeroes' in 100 tell you to move the decimal point exactly TWO places to the right.
MISTAKE: Forgetting to add zeros if there aren't enough digits after the decimal point. For example, multiplying 0.5 by 100 and getting 5.0. | CORRECTION: If you run out of digits, add zeros as placeholders. For 0.5 x 100, move one place (5.), then add a zero and move another place (50.). The answer is 50.
Practice Questions
Try It Yourself
QUESTION: What is 6.25 multiplied by 100? | ANSWER: 625
QUESTION: An auto-rickshaw travels 0.875 km on one litre of a special fuel. How many kilometres would it travel on 100 litres? | ANSWER: 87.5 km
QUESTION: A tiny computer chip is 0.034 cm thick. If 100 such chips are stacked one on top of another, what would be the total height of the stack in cm? | ANSWER: 3.4 cm
MCQ
Quick Quiz
What is the result of 0.007 multiplied by 100?
0.00007
0.07
0.7
7
The Correct Answer Is:
C
Multiplying by 100 means moving the decimal point two places to the right. Starting with 0.007, moving it one place gives 0.07, and moving it a second place gives 0.7.
Real World Connection
In the Real World
When you buy gold or silver, prices are often quoted per gram (e.g., Rs 65.50 per gram). If you want to know the price for 100 grams, you would multiply the per-gram price by 100. This calculation is done by jewellers and customers every day across India.
Key Vocabulary
Key Terms
DECIMAL: A number that includes a decimal point, representing a whole number and a fractional part. | MULTIPLY: To combine numbers to find their total product. | DECIMAL POINT: The dot in a decimal number that separates the whole number part from the fractional part. | PLACEHOLDER ZERO: A zero added to maintain the correct value or position of digits.
What's Next
What to Learn Next
Great job learning about multiplying decimals by 100! Next, you should explore 'Multiplying Decimals by 1000'. This will build on the same idea of moving the decimal point, but with a slightly different number of places, making you even better at decimal calculations!
