What is Adding to Make Eighteen?

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Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Adding to Make Eighteen means finding two or more numbers that, when put together, give you a total sum of 18. It's about combining quantities to reach a specific target number, which in this case is eighteen.

Simple Example

Quick Example

Imagine you have 10 cricket balls and your friend gives you some more. If you now have 18 cricket balls in total, how many did your friend give you? You added 8 balls to your 10 to reach 18.

Worked Example

Step-by-Step

Let's say you want to buy a toy car that costs Rs. 18. You have Rs. 12 with you. How much more money do you need?

Step 1: Identify the total amount needed: Rs. 18.
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Step 2: Identify the amount you already have: Rs. 12.
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Step 3: Think: "What number, when added to 12, gives me 18?"
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Step 4: You can count up from 12: 13, 14, 15, 16, 17, 18. That's 6 steps.
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Step 5: So, 12 + 6 = 18.
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Answer: You need Rs. 6 more.

Why It Matters

Understanding how numbers combine to make a specific total is a basic building block for all math! It helps you manage your pocket money, plan ingredients for a recipe, or even understand scores in a game. Engineers, scientists, and even shopkeepers use this skill every day.

Common Mistakes

MISTAKE: Confusing 'adding to make 18' with 'subtracting 18 from a number'. | CORRECTION: Remember 'adding to make' means you are finding a missing part that completes the total, not taking away from it.

MISTAKE: Only thinking about two numbers that add up to 18. | CORRECTION: Many numbers can add up to 18, like 5 + 5 + 8 = 18. Don't limit yourself to just two parts.

MISTAKE: Guessing the answer instead of using a method like counting on or subtraction. | CORRECTION: To find the missing number, you can subtract the known number from 18. For example, if you have 7, then 18 - 7 = 11.

Practice Questions

Try It Yourself

QUESTION: Your mom gave you 9 laddoos. Your aunt gave you some more. Now you have 18 laddoos. How many did your aunt give you? | ANSWER: 9 laddoos

QUESTION: A bus has 18 seats. 11 seats are already taken. How many more passengers can sit? | ANSWER: 7 passengers

QUESTION: You have three friends. Friend A has 5 stickers, Friend B has 6 stickers. How many stickers does Friend C need to have so that all three friends have 18 stickers in total? | ANSWER: 7 stickers (5 + 6 = 11; 18 - 11 = 7)

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. The other options are 7+9=16, 6+11=17, and 5+12=17, none of which equal 18.

Real World Connection

In the Real World

When you are shopping at a local kirana store and the total bill is Rs. 18, and you pay with a Rs. 20 note, the shopkeeper quickly calculates the change by thinking 'what plus 18 makes 20?'. This is a real-life application of adding to make a total.

Key Vocabulary

Key Terms

ADDITION: The process of combining numbers to find their total sum | SUM: The result of adding two or more numbers | TOTAL: The complete amount or number | COMBINE: To put things together | MISSING NUMBER: The unknown number needed to complete an equation

What's Next

What to Learn Next

Great job understanding adding to make 18! Next, you can learn about 'Adding to Make Twenty' or 'Adding to Make One Hundred'. These concepts build on the same idea but help you work with larger numbers more confidently.