What is Counting by Threes?

S0-SA1-0989

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Counting by Threes means skipping two numbers and saying the third number in a sequence. You start from a number and keep adding 3 to get the next number in the count. It helps us count things faster in groups of three.

Simple Example

Quick Example

Imagine you have a stack of laddoos, and each small box has 3 laddoos. If you count by threes, you'd say: 3 (for the first box), 6 (for two boxes), 9 (for three boxes), and so on. This way, you quickly know how many laddoos you have without counting each one individually.

Worked Example

Step-by-Step

Let's count by threes starting from 0 up to 15.

Step 1: Start with 0.

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Step 2: Add 3 to the starting number: 0 + 3 = 3.

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Step 3: Add 3 to the new number: 3 + 3 = 6.

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Step 4: Add 3 to the new number: 6 + 3 = 9.

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Step 5: Add 3 to the new number: 9 + 3 = 12.

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Step 6: Add 3 to the new number: 12 + 3 = 15.

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The numbers when counting by threes from 0 to 15 are: 0, 3, 6, 9, 12, 15.

Why It Matters

Counting by threes is a basic skill that helps you understand patterns in numbers and learn multiplication tables faster. It's useful in many jobs like a shopkeeper quickly calculating the cost of items sold in packs of three, or a carpenter measuring wood for projects, or even a chef planning ingredients for recipes.

Common Mistakes

MISTAKE: Skipping too many or too few numbers, for example, saying 3, 7, 10. | CORRECTION: Always add exactly 3 to the previous number. So, after 3, the next number is 3 + 3 = 6, not 7.

MISTAKE: Forgetting where you started or losing track of the sequence, like saying 3, 6, 9, 11. | CORRECTION: Practice counting aloud and use your fingers or a number line to keep track. Make sure each jump is exactly 3.

MISTAKE: Confusing counting by threes with counting by twos or fours. For example, saying 2, 4, 6, 8 instead of 3, 6, 9, 12. | CORRECTION: Remember the specific number you are counting by. For 'counting by threes,' always use the number 3.

Practice Questions

Try It Yourself

QUESTION: Count by threes, starting from 0, up to 18. | ANSWER: 0, 3, 6, 9, 12, 15, 18

QUESTION: If you have 5 groups of 3 pencils each, how many pencils do you have in total? Count by threes to find out. | ANSWER: 3, 6, 9, 12, 15 pencils.

QUESTION: A tailor stitches 3 buttons on each shirt. If he has finished 7 shirts, how many buttons has he used in total? Count by threes starting from 0. | ANSWER: 0, 3, 6, 9, 12, 15, 18, 21 buttons.

MCQ

Quick Quiz

Which of these sequences shows counting by threes?

2, 4, 6, 8

3, 6, 9, 12

1, 2, 3, 4

5, 10, 15, 20

The Correct Answer Is:

Option B (3, 6, 9, 12) is correct because each number is 3 more than the previous one. Options A, C, and D are counting by twos, ones, and fives respectively.

Real World Connection

In the Real World

In India, counting by threes is super useful. Think about buying samosas – often they are sold in packs of 3 or 6. A shopkeeper quickly calculates the price by counting by threes. Or when you're playing carrom, if each player gets 3 coins, you can count by threes to see how many coins are needed for everyone.

Key Vocabulary

Key Terms

SEQUENCE: A set of numbers or items that follow a pattern | ADDITION: The process of combining numbers to find their total | PATTERN: A regular, repeating way in which something happens or is done | SKIP COUNTING: Counting by a number other than one, like two, three, or five

What's Next

What to Learn Next

Great job learning to count by threes! Now that you understand this, you can easily move on to 'Counting by Fives' and 'Counting by Tens.' These concepts build on the same idea of skip counting and will make multiplication even simpler for you.