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What is 9 × 11?
Grade Level:
Class 3
Maths, Computing, AI
Definition
What is it?
The question 'What is 9 × 11?' asks for the product when the number 9 is multiplied by the number 11. It means adding the number 9 to itself 11 times, or adding the number 11 to itself 9 times.
Simple Example
Quick Example
Imagine you have 9 friends, and each friend brings 11 laddoos to a party. To find out the total number of laddoos, you would multiply 9 by 11. This helps you quickly find the total without counting each laddoo one by one.
Worked Example
Step-by-Step
Let's find the answer to 9 × 11 using repeated addition.
1. We need to add 9 to itself 11 times.
2. Start with the first 9: 9
3. Add another 9: 9 + 9 = 18
4. Add another 9: 18 + 9 = 27
5. Add another 9: 27 + 9 = 36
6. Add another 9: 36 + 9 = 45
7. Add another 9: 45 + 9 = 54
8. Add another 9: 54 + 9 = 63
9. Add another 9: 63 + 9 = 72
10. Add another 9: 72 + 9 = 81
11. Add another 9: 81 + 9 = 90
12. Add the last 9: 90 + 9 = 99
So, 9 × 11 = 99.
Why It Matters
Multiplication is a basic skill used in everyday life and is fundamental to advanced studies in Maths, Computing, and AI. Understanding multiplication tables helps engineers design complex systems, data analysts process large datasets, and even AI programmers create efficient algorithms. It's a stepping stone to careers in software development, data science, and robotics.
Common Mistakes
MISTAKE: Adding 9 and 11 instead of multiplying (9 + 11 = 20) | CORRECTION: Remember that '×' means multiplication, which is repeated addition, not simple addition.
MISTAKE: Forgetting multiplication tables and guessing | CORRECTION: Practice your multiplication tables regularly. Knowing them by heart makes calculations much faster and more accurate.
MISTAKE: Miscalculating during repeated addition (e.g., 9+9=17) | CORRECTION: Double-check each step in repeated addition. Break down the problem or use known facts like 9 x 10 = 90, then add one more 9.
Practice Questions
Try It Yourself
QUESTION: If a bus ticket costs Rs 9, how much will 5 tickets cost? | ANSWER: Rs 45
QUESTION: A gardener plants 9 saplings in each row. If he plants 12 such rows, how many saplings did he plant in total? | ANSWER: 108 saplings
QUESTION: A shopkeeper sells 9 packets of biscuits every day. Each packet has 10 biscuits. How many biscuits does he sell in 2 days? | ANSWER: 180 biscuits (9x10 = 90 biscuits per day; 90x2 = 180 biscuits in 2 days)
MCQ
Quick Quiz
What is the product of 9 and 11?
20
99
100
91
The Correct Answer Is:
B
The product of 9 and 11 is 99. This can be found by adding 9 eleven times or by using the multiplication table for 9 or 11.
Real World Connection
In the Real World
When you buy 9 notebooks, and each notebook costs Rs 11, you use multiplication to calculate the total bill: 9 × 11 = Rs 99. This is similar to how shopkeepers use multiplication in their billing software or how you budget for your pocket money or calculate cricket scores.
Key Vocabulary
Key Terms
MULTIPLY: To combine numbers by repeated addition to find a total | PRODUCT: The result of multiplication | TIMES: Another word for 'multiplied by' | FACTOR: Numbers that are multiplied together to get a product
What's Next
What to Learn Next
Great job mastering 9 × 11! Next, you can explore larger multiplication problems, like 'What is 12 × 15?'. Understanding basic multiplication tables like this will make solving bigger problems much easier and faster!
