What is Subtracting from Eighteen?

S0-SA1-1354

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Subtracting from eighteen means taking away a certain number from the total number eighteen. It helps us find out how much is left after a part is removed. This is a basic operation in arithmetic.

Simple Example

Quick Example

Imagine you have 18 laddoos in a box. Your younger brother eats 5 laddoos. To find out how many laddoos are left, you subtract 5 from 18. This gives you the remaining number of laddoos.

Worked Example

Step-by-Step

Let's say a cricket team needs 18 runs to win. They have already scored 12 runs. How many more runs do they need?
---Step 1: Identify the total amount. The total runs needed are 18.
---Step 2: Identify the amount to be taken away. The runs already scored are 12.
---Step 3: Set up the subtraction problem: 18 - 12.
---Step 4: Subtract the ones place: 8 - 2 = 6.
---Step 5: Subtract the tens place: 1 - 1 = 0.
---Step 6: Combine the results. So, 18 - 12 = 6.
---Answer: The team needs 6 more runs to win.

Why It Matters

Understanding subtraction from eighteen helps you manage daily finances, like calculating change at the local kirana store. It's a fundamental skill for careers in business, accounting, and even engineering, where precise calculations are crucial.

Common Mistakes

MISTAKE: Subtracting the larger number from the smaller number when the smaller number is first (e.g., trying to do 5 - 18 instead of 18 - 5) | CORRECTION: Always subtract the smaller number from the larger number in simple subtraction problems, or understand that the result will be a negative number.

MISTAKE: Forgetting to borrow when needed in multi-digit subtraction (e.g., in 18 - 9, thinking 8-9 is impossible and guessing) | CORRECTION: When the digit in the ones place is smaller than the digit being subtracted, borrow 1 'ten' from the tens place, making the ones digit 10 more (e.g., 18 becomes 0 tens and 18 ones for the ones place).

MISTAKE: Mixing up addition and subtraction signs, especially in word problems | CORRECTION: Read the problem carefully for keywords like 'left,' 'remaining,' 'taken away,' or 'difference' which usually indicate subtraction.

Practice Questions

Try It Yourself

QUESTION: You had 18 stickers and gave 7 to your friend. How many stickers do you have left? | ANSWER: 11 stickers

QUESTION: A bus has 18 seats. If 9 seats are empty, how many passengers are on the bus? | ANSWER: 9 passengers

QUESTION: Riya had 18 rupees. She bought a pencil for 5 rupees and an eraser for 3 rupees. How much money does she have left? | ANSWER: 10 rupees

MCQ

Quick Quiz

What is 18 minus 6?

The Correct Answer Is:

18 minus 6 means taking 6 away from 18. If you count back 6 steps from 18, you land on 12. So, 18 - 6 = 12.

Real World Connection

In the Real World

When you pay for your groceries with a 20 rupee note and the total bill is 18 rupees, the shopkeeper needs to calculate the change. They mentally subtract 18 from 20 to give you 2 rupees back. This is similar to subtracting from eighteen, just with a different starting number.

Key Vocabulary

Key Terms

SUBTRACT: To take away one number from another to find the difference | DIFFERENCE: The result of subtracting one number from another | MINUS: A symbol (-) indicating subtraction | REMAINDER: The amount left after subtraction

What's Next

What to Learn Next

Now that you understand subtracting from eighteen, you can move on to 'Subtracting Larger Numbers' or 'Subtraction with Borrowing'. These concepts will build on your current understanding and help you solve more complex problems.