Number Bond Superpowers: Your Secret Code for Mental Maths!

Hi Maths Superstars! Did you know you already have secret codes that can help you solve maths problems super fast in your head? These secret codes are called Number Bonds! They are pairs of numbers that “bond” together to make another number, like 7+3=10, or 15+5=20. Today, we’re going to learn how to use your amazing knowledge of number bonds to 10, 20, and 100 to make mental addition and subtraction a breeze!

How Do Number Bonds Help Us Add and Subtract?

Knowing your number bonds well means you can spot them inside bigger numbers and use them to break problems down into easier steps.

Example 1: Using Number Bonds to 10 in Addition (like 135 + 7)

Let’s look at 135 + 7.

• Focus on the ones digits: In 135, the ones digit is 5. We are adding 7.
• Do you know the number bond for 5 + 7? That’s right, 5 + 7 = 12.
• So, the ones part of our answer will be from that ’12’. The ‘2’ is our new ones digit.
• The ‘1’ from the ’12’ is an extra ten! So we add that 1 ten to the 3 tens in 135, making it 4 tens.
• The hundred (1 hundred) stays the same.
• So, 135 + 7 becomes 1 hundred, 4 tens, and 2 ones: 142.
  • Another way to think about 135+7 with bonds: How much does 5 need to make 10? It needs 5. So, take 5 from the 7 (7-5=2 left). 135+5 = 140. Then add the leftover 2: 140+2 = 142. This is called “Making a Ten.”

Example 2: Using Number Bonds to 20 in Subtraction (like 48 − 16)

Let’s try 48 − 16.

• We can think about the number 16. How can we use bonds to subtract it easily?
• Maybe we know that 16 is close to 20. A number bond for 20 is 16 + 4 = 20.
• So, if we subtract 20 from 48, that’s easy: 48 − 20 = 28.
• But we only wanted to subtract 16, and we subtracted 20 (which is 4 too much).
• So, we need to add that 4 back on: 28 + 4 = 32.
• Therefore, 48 − 16 = 32. (This uses a “compensating” strategy with bonds).

Example 3: Using Number Bonds to 100 for “Making a Hundred” (like 295 + 8)

Let’s look at 295 + 8.

• 295 is very close to 300. What number bond with 95 makes 100? 95 + 5 = 100. So 295 needs 5 more to get to 300.
• Let’s take that 5 from the 8 we are adding. (8 − 5 = 3 left over).
• So, 295 + 5 = 300.
• Now add the leftover 3: 300 + 3 = 303.
• So, 295 + 8 = 303.

Your Mission: Use Your Number Bond Powers! (18 Questions)

Now it’s your turn to use these number bond strategies! For each question below, think about which number bonds (to 10, 20, or 100) can help you find the answer in your head.

(Your web app with the 18 questions will go here. The questions should be designed to encourage the use of different number bond strategies.)

Why Are Number Bond Strategies So Amazing?

• Makes Maths Faster: You can solve problems much more quickly by using facts you already know.
• Reduces Mistakes: Breaking problems down with bonds often means fewer steps to get muddled with.
• Builds Big Confidence: When you see how these “secret codes” work, you’ll feel like a maths genius!
• Helps with All Sorts of Maths: This strategy is useful for almost any addition or subtraction you’ll ever do!

Guidance for Parents & Teachers: Reinforcing Number Bonds

This activity encourages children to apply their recall of number bonds to 10, 20, and 100 as a flexible strategy to simplify mental addition and subtraction. The goal is to move beyond rote counting to strategic calculation.

• Regular Recall Practice: Quick, fun games to recall number bonds to 10, 20, and 100 are essential (e.g., “What goes with 7 to make 10?”, “What goes with 13 to make 20?”).
• Encourage “Making Ten/Hundred”: When adding, prompt children to see if they can make the next multiple of 10 or 100 first. For 135+7, ask “How many does 5 need to make 10?”
• Discuss Different Strategies: After solving a problem, ask, “How did you work that out? Did you use a number bond?” Highlight that different bonds or strategies can lead to the same answer.
• Model Your Thinking: When you solve a problem mentally, talk through how you use number bonds. “For 63-8, I think 63-3 is 60, then I need to take away 5 more, so 60-5 is 55.”