Concept 3 of 9
Adding 2-Digit Numbers
Today's big idea
Line up ones under ones and tens under tens, then add each column.
34 + 25: ones 4+5=9, tens 3+2=5 → 59.
How it works
👀 What's going on?
34 + 25 is too big for fingers. Stack the numbers instead.
💡 Here's the trick
Line up ones under ones and tens under tens, then add each column on its own.
34 + 25: ones 4 + 5 = 9, tens 3 + 2 = 5. The answer is 59.
✍️ Try it
Add 52 + 26. Ones 2 + 6 = 8, tens 5 + 2 = 7. → 78.
⚠️ Watch out
Keep ones under ones, or the columns get mixed up.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Add 61 + 27.”
- 1
Add the ones
1 + 7 = 8.
- 2
Add the tens
6 + 2 = 8.
- 3
Answer ✓
61 + 27 = 88
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Add the ones column.
34 + 25
4 + 5 = ?
Quick check
✅ VERIFICATION
What is 43 + 25?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Subtracting 2-Digit Numbers
Line up the columns, then subtract each one.