Decompose Numbers to 5

Kindergarten · mathematics · 75 practice problems · read aloud

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Decompose Numbers to 5 🧩

What is Decomposing?

Decomposing a number is like breaking it into smaller parts. For the number 5, you can break it into 2 and 3, or 4 and 1. It helps us understand how numbers are built, which makes adding and subtracting much easier!

How to Decompose Numbers

  1. Pick a Number: Start with a number like 5.
  2. Find the Parts: Use counters, your fingers, or drawings to find two groups that make your number.
  3. Write the Equation: Show your work as a number sentence, like 5 = 2 + 3.

Let's Look at Examples

Example 1: Decomposing 4

We have 4 stars. Let's break them apart.

⭐️⭐️ | ⭐️⭐️

One group has 2 stars, the other has 2 stars. So, 4 = 2 + 2.

Example 2: Decomposing 5

We have 5 circles. Let's break them apart a different way.

⚫️⚫️⚫️ | ⚫️⚫️

One group has 3 circles, the other has 2 circles. So, 5 = 3 + 2.

Watch Out! Common Mistakes

➡️ Forgetting Zero: Remember, a number can be broken into itself and zero! 5 = 5 + 0 is a correct way to decompose.

➡️ Miscounting: Always double-check your parts. If you add them back together, they must equal your starting number.

Fun Tips & Tricks

🎯 Use Your Fingers: Hold up the number on one hand. Put some fingers down to see the two parts!

🎯 Sing a Song: "5 little monkeys, jumping on the bed. One fell off, and now there are 4!" This shows 5 = 1 + 4.

Time to Practice!

  • Gather 5 small toys or blocks. See how many different ways you can split them into two groups.
  • Ask a grown-up to say a number (2, 3, 4, or 5). Shout out as many number pairs that make it as you can!
  • Draw pictures. Draw 5 flowers, then circle different groups of them to show the parts.

Practice problems

6 of the 75, worked through step by step — try them before opening the answer.

1 5 = 2 + ?

Hint: Think about what number you need to add to the given number to make the total.

Show the answer

Answer: 3

  1. The equation says that 5 is equal to 2 plus some unknown number. We can rewrite it as: 2 + ? = 5
  2. To find the unknown number, we need to get it alone on one side. We can do this by subtracting 2 from both sides of the equation: 2 + ? - 2 = 5 - 2
  3. On the left side, 2 - 2 is 0, so we are left with: ? = 5 - 2
  4. Now calculate 5 - 2: 5 - 2 = 3
  5. Therefore, the unknown number is 3. Final answer: 3

We start with the equation: 5 = 2 + ?

2 5 = 4 + ?

Hint: Think about what number you need to add to make the total

Show the answer

Answer: 1

  1. We know that 5 = 4 + ?
  2. Think about what number added to 4 makes 5
  3. 4 + 1 = 5
  4. So the missing number is 1

The answer is 1.

3 4 = 1 + ?

Hint: Think about what number you need to add to 1 to make 4.

Show the answer

Answer: 3

  1. We know that 4 is the total.
  2. We know one part is 1.
  3. To find the missing part, think: 1 plus what number equals 4?
  4. 1 + 3 = 4

The answer is 3.

4 3 = 1 + ?

Hint: Think about what number you need to add to 1 to make 3

Show the answer

Answer: 2

  1. We know that 3 = 1 + ?
  2. This means we need to find what number plus 1 equals 3
  3. If we start with 1, we need to add 2 more to get to 3
  4. 1 + 2 = 3
  5. Therefore, the missing number is 2

5 0 = ? + 0

Hint: Think about how you can split this number into two parts that add up to the total.

Show the answer

Answer: 0

Since 0 + 0 = 0, we know that 0 = 0 + 0.

6 1 = ? + 1

Hint: Think about how you can split this number into two parts that add up to the total.

Show the answer

Answer: 0

Since 0 + 1 = 1, we know that 1 = 0 + 1.

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