What is Adding to Make 18?

S0-SA1-1291

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Adding to make 18 means finding two or more numbers that, when put together, give you a total of 18. It's about understanding different combinations of numbers that sum up to 18.

Simple Example

Quick Example

Imagine you have 10 marbles. Your friend gives you some more marbles, and now you have a total of 18 marbles. How many marbles did your friend give you? You started with 10, and you need to reach 18, so your friend gave you 8 marbles (10 + 8 = 18).

Worked Example

Step-by-Step

Let's say you want to score 18 runs in a cricket match with two hits. If your first hit was a boundary (4 runs), how many runs do you need on your second hit to reach 18?

1. Start with the target score: 18 runs.
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2. Note down the runs already scored: 4 runs.
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3. To find out how many more runs are needed, subtract the runs already scored from the target score: 18 - 4.
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4. Perform the subtraction: 18 - 4 = 14.
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5. So, you need 14 more runs on your second hit.

Answer: You need to hit 14 runs.

Why It Matters

Understanding how numbers combine to make a total is fundamental to all math. This skill helps in daily tasks like calculating change, managing pocket money, or even understanding scores in games. It's a basic building block for careers in finance, engineering, and data analysis.

Common Mistakes

MISTAKE: Confusing addition with subtraction when finding the missing number. For example, calculating 18 - 5 when the question is 5 + ? = 18 and thinking the answer is 13, but then saying 18 - 5 directly is the answer. | CORRECTION: Always check if the operation is addition or subtraction. If you have a part and the total, subtraction helps find the other part. If you have two parts, addition finds the total.

MISTAKE: Not checking the answer. Students might quickly guess a number without verifying if it actually adds up to 18. For example, thinking 9 + 8 = 18. | CORRECTION: After finding your answer, always add it back to the given number to see if it truly equals 18. (9 + 8 = 17, not 18, so 9 + 9 = 18 is correct).

MISTAKE: Only considering single-digit numbers. Sometimes, the missing number could be a two-digit number. For example, in 3 + ? = 18, thinking the answer must be a single digit. | CORRECTION: Remember that numbers can be single-digit or double-digit. 3 + 15 = 18, where 15 is a two-digit number.

Practice Questions

Try It Yourself

QUESTION: Your mom gave you 7 ladoos. How many more ladoos do you need to have a total of 18? | ANSWER: 11

QUESTION: In a game, you scored 6 points in the first round and 5 points in the second round. How many more points do you need to reach a total score of 18? | ANSWER: 7

QUESTION: You are collecting stickers. You have 9 stickers, and your friend gives you 3 more. How many more stickers do you still need to have exactly 18 stickers in total? | ANSWER: 6

MCQ

Quick Quiz

Which pair of numbers adds up to 18?

7 and 9

8 and 10

6 and 11

5 and 12

The Correct Answer Is:

8 + 10 equals 18. Options A, C, and D do not add up to 18 (7+9=16, 6+11=17, 5+12=17).

Real World Connection

In the Real World

When you're shopping for groceries using a digital payment app like UPI, you might have Rs 10 in your e-wallet and need to pay Rs 18. Knowing 'what is adding to make 18' helps you quickly figure out you need to add Rs 8 to your wallet to complete the payment.

Key Vocabulary

Key Terms

ADDITION: The process of combining numbers to find their total | SUM: The total result of adding two or more numbers | COMBINATION: A set of numbers that, when added, produce a specific total | TOTAL: The whole amount or number

What's Next

What to Learn Next

Great job understanding adding to make 18! Next, you can learn about 'Adding to Make 20' or 'Fact Families for 18'. These concepts will help you build on your addition skills and understand how numbers relate to each other, making more complex math easier.