Concept 3 of 6
The Place-Value House: Ones, Tens, Hundreds
Today's big idea
A digit's room decides its value, so the same digit can mean 3 or 300.
Rooms are counted from the right: ones, tens, then hundreds.
How it works
👀 What's going on?
The 5 in 5 and the 5 in 500 look the same. Are they worth the same?
💡 Here's the trick
A digit's room decides its value. From the right: ones, then tens, then hundreds. Each room is ten times bigger than the one beside it.
In 342, the 3 is in the hundreds room (300), the 4 in tens (40), the 2 in ones (2).
✍️ Try it
In 268, what is the 2 worth? It sits in hundreds, so it is worth 200.
⚠️ Watch out
Count the rooms from the right, never from the left.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“In 586, what is the 8 worth?”
- 1
Name the rooms from the right
Ones is 6, tens is 8, hundreds is 5.
- 2
Find where the 8 sits
The 8 is in the tens room.
- 3
Read off its value
8 in the tens room means 8 tens, which is 80.
- 4
Answer ✓
80
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Drag the 🔍 X-ray scanner across the number to reveal the value hiding inside each digit. Then tap the digit that hides 50 to lock it in.
Which digit is worth 50? Scan, then tap to lock it in!
Drag the lens left and right
Quick check
✅ VERIFICATION
In 473, what is the place value of the 7?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Expanded Form & Number Names
342 = 300 + 40 + 2, one number in three forms.