Making Ten: The Trick Behind Fast Addition
Look at your two hands. Ten fingers, right? For thousands of years, people have used groups of ten to count faster, and you can use that same trick today. When you learn to 'make a ten,' adding numbers like 8 + 5 gets easy — you can do it in your head without counting one by one.
What You'll Learn
By the end of this lesson you will be able to: - Break a number into two smaller parts - Use those parts to build a group of ten - Add two numbers by making a ten first - Solve addition problems faster without counting on your fingers
Ten Is a Superhero Number
Our number system is built on groups of ten. That's why every number has a ones place and a tens place. When two numbers add up close to ten, like 8 and 5, you can move a little piece from one number to the other to build a perfect ten. Once you have a ten, the rest of the adding is easy, because 10 plus anything just means writing a 1 in front of that anything.
The Make-a-Ten Trick, Step by Step
Let's solve 8 + 5. Step 1: Look at 8. It needs 2 more to become 10. Step 2: Break the 5 into 2 and 3, because 2 + 3 = 5. Step 3: Give the 2 to the 8. Now you have 10 + 3. Step 4: 10 + 3 = 13. So 8 + 5 = 13!
Ask yourself: which number is closer to 10? Take pieces from the OTHER number to fill it up. That's the whole trick.
Practice With Bigger Numbers
Try 9 + 6. The 9 needs just 1 more to become 10. Break 6 into 1 and 5. Give the 1 to the 9: now it's 10 + 5 = 15. Now try 7 + 8. The 7 needs 3 more to become 10. Break 8 into 3 and 5. Give the 3 to the 7: now it's 10 + 5 = 15.
What is 8 + 6 using the make-a-ten trick?
Which pair would you split to solve 9 + 7 using make a ten?
Build a Tower of Ten
Grab 20 small objects like blocks, buttons, or dried beans. Pick two numbers that add up between 11 and 18 (like 8 and 7). Build one pile with the first number and one pile with the second number. Move pieces from one pile to the other until the first pile has exactly 10. Count what's left in the second pile. Write down the make-a-ten equation you built, like '8 + 7 = 10 + 5 = 15,' and show it to a family member.
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