Concept 2 of 7
Number Smashers: The Partition Method
Today's big idea
Smash into hundreds, tens and ones, add each pile, then recombine.
246 + 375: 500 + 110 + 11 = 621.
How it works
👀 What's going on?
Add 328 + 245 in your head? Smash each number into hundreds, tens and ones, and it becomes three easy sums.
💡 Here's the trick
Look at the picture above. Split each number into its hundreds, tens and ones. Add the three hundreds-piles, the tens-piles and the ones-piles, then join them into one number.
🪄 How to do it
- 1.Smash each number into hundreds, tens and ones (328 becomes 300, 20 and 8).
- 2.Add the hundreds pile, the tens pile, and the ones pile.
- 3.Join the three piles together.
✍️ Try it
Smash 231 + 145. Then smash 264 + 158.
200+100=300, 30+40=70, 1+5=6, so 300+70+6=376. And 200+100=300, 60+50=110, 4+8=12, so 300+110+12=422.
⚠️ Watch out
When a pile tops its place, do not lose the spare. 60 + 50 = 110 is one hundred and one ten, and that spare hundred is exactly what carrying moves.
🌟 Why this matters
Smashing shows WHY the column method carries, and it makes adding big numbers in your head far easier. To subtract, smash both numbers and take each pile away.
Exam tip: a quick smash is the fastest way to check a column answer that looks wrong.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Add 328 + 245 by smashing into hundreds, tens and ones.”
- 1
Smash both numbers
328 = 300+20+8, 245 = 200+40+5.
- 2
Add the hundreds pile
300 + 200 = 500.
- 3
Add the tens pile
20 + 40 = 60.
- 4
Add the ones pile
8 + 5 = 13.
- 5
Put them together
500 + 60 + 13 = 573.
- 6
Answer ✓
328 + 245 = 573
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Smash each number into hundreds, tens and ones. Add each pile, then put them back together.
246 + 375 = ?
Add the hundreds: 200 + 300 = ?
Quick check
✅ VERIFICATION
Smash 342 + 215: hundreds 300+200 = 500, tens 40+10 = 50, ones 2+5 = 7. What is the total?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Add It Up
Carry the extra when a column overflows.