Adding Three Numbers
You already know how to add two numbers: 3 + 4 = 7. But what if there are THREE numbers? Like 2 + 3 + 4. Don't worry — you can do it! There's a cool trick: you can add any two first, then add the third.
Add any two first
For 2 + 3 + 4, you have choices:\n\n- Add 2 + 3 first = 5. Then 5 + 4 = 9. ✅\n- Add 3 + 4 first = 7. Then 7 + 2 = 9. ✅\n- Add 2 + 4 first = 6. Then 6 + 3 = 9. ✅\n\nAll three give you **9**! This is a rule of math: you can add numbers in any order and you'll get the same answer. That's called **commutative and associative properties** (fancy words, but the idea is simple).
What is 1 + 2 + 3?
Pick the easy pair
Since you get to choose which two numbers to add first — **pick the easiest!**\n\n🧠 **Doubles are easy:** 3 + 3 = 6, 4 + 4 = 8. You might know these by heart.\n\n🧠 **Making 10 is easy:** 7 + 3 = 10, 6 + 4 = 10, 8 + 2 = 10.\n\n**Example:** Solve 7 + 3 + 5.\n- Smart move: add 7 + 3 first = 10. Then 10 + 5 = 15. Easy!\n- Harder way: add 7 + 5 first = 12. Then 12 + 3 = 15. (Still right, but took more thinking.)\n\nSpot the easy pair — then add it first!
Which pair should you add FIRST in 6 + 4 + 3?
Count on, when you need to
Sometimes the numbers don't make a neat pair. That's OK — just count on with your fingers or a number line.\n\n**Example:** 4 + 3 + 2.\n- 4 + 3 = 7 (count up 3 from 4: 5, 6, 7)\n- 7 + 2 = 9 (count up 2 from 7: 8, 9)\n\nYou've got this!
Three-number dice
Roll 3 dice (or use a dice app). Write down the three numbers. Look for the easy pair FIRST (does any pair make 10? Are any the same?). Add them first, then add the third. Do this 5 times. Each time, explain which pair you chose and why.
Ten-frames trick
Using two 10-frames (draw them on paper as 2 rows of 5 boxes), show 8 + 2 + 5. First, fill up a frame with 8 dots, then 2 dots — that makes a full 10! Then fill the second frame with 5 more dots. Total: 15. Making a 10 first is the easiest way to add three numbers.
Solve 5 + 5 + 2.
Adding three numbers is a big-kid math skill. Once you get good at looking for easy pairs (10-makers and doubles), you'll add faster than ever. This trick keeps working for four numbers, five numbers — forever! You just unlocked a tool real mathematicians use.
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