What is Multiplying by Twelve?

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Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Multiplying by twelve means adding the same number twelve times. It's a quick way to find the total when you have twelve equal groups of something. Think of it as '12 times' a number.

Simple Example

Quick Example

Imagine you get 12 laddoos in each box from the sweet shop. If you buy 3 such boxes, how many laddoos do you have in total? You can add 12 + 12 + 12, or simply multiply 3 by 12.

Worked Example

Step-by-Step

Let's find out how many hours are in 5 days. We know there are 24 hours in 1 day. So, we need to multiply 24 by 5.

---Step 1: Write down the multiplication problem: 24 x 5.

---Step 2: Multiply the ones digit: 5 x 4 = 20. Write down 0 in the ones place and carry over 2 to the tens place.

---Step 3: Multiply the tens digit: 5 x 2 = 10. Add the carried-over 2: 10 + 2 = 12.

---Step 4: Write down 12 next to the 0. So, 24 x 5 = 120.

---Answer: There are 120 hours in 5 days.

Why It Matters

Understanding multiplication helps you quickly solve problems in daily life and in higher math. It's crucial for careers like shopkeepers managing inventory, engineers calculating materials, or even data scientists analyzing patterns. It builds a strong foundation for algebra and more complex calculations.

Common Mistakes

MISTAKE: Forgetting to carry over numbers when multiplying. For example, in 15 x 3, students might do 3x5=15 (write 5, carry 1), then 3x1=3, and forget to add the carried 1, giving 35 instead of 45. | CORRECTION: Always remember to add the carried-over digit to the product of the next place value.

MISTAKE: Confusing multiplication with addition. Students might add 12 to a number instead of multiplying it. For example, for '12 times 5', they might say 12 + 5 = 17. | CORRECTION: Remember that 'times' means repeated addition. 12 times 5 means 5 added 12 times (or 12 added 5 times).

MISTAKE: Not knowing the multiplication tables for smaller numbers, which slows down multiplying by larger numbers like 12. | CORRECTION: Practice your multiplication tables (up to 10 or 12) regularly. This makes multiplying by any number much faster and easier.

Practice Questions

Try It Yourself

QUESTION: A auto-rickshaw driver charges ₹12 per kilometer. How much will he charge for a 7-kilometer ride? | ANSWER: ₹84

QUESTION: If a cricket team scores 12 runs in each of 15 overs, how many runs have they scored in total? | ANSWER: 180 runs

QUESTION: A factory produces 25 units of a product every hour. If it runs for 12 hours a day, and operates for 6 days a week, how many units are produced in one week? | ANSWER: 1800 units

MCQ

Quick Quiz

What is 12 multiplied by 9?

108

129

The Correct Answer Is:

12 multiplied by 9 means adding 12 nine times (12+12+12+12+12+12+12+12+12) or 9 twelve times (9+9+9+9+9+9+9+9+9+9+9+9). Both result in 108.

Real World Connection

In the Real World

Multiplying by twelve is used often! For example, when you calculate your monthly mobile data usage if you use 12 GB every month, or when a shopkeeper counts how many items are in 12 cartons, each with 20 items. Even in construction, engineers multiply dimensions by 12 (for inches to feet conversion, though less common in India) or other numbers to find total areas or volumes.

Key Vocabulary

Key Terms

MULTIPLY: To combine numbers by repeated addition | PRODUCT: The result of multiplication | FACTOR: A number that is multiplied by another number | CARRY OVER: Moving a digit from one place value column to the next higher one during addition or multiplication

What's Next

What to Learn Next

Now that you understand multiplying by twelve, you can explore multiplying by larger numbers or even two-digit numbers. This will help you solve even bigger problems and prepare you for concepts like area, volume, and percentages.