Extend your abacus to three rods and unlock numbers from 100 to 999. Learn the place value of the hundreds rod and build any three-digit number confidently.
By the end of this lesson you will be able to— இந்த பாடத்தின் இறுதியில்
- Identify the hundreds rod and its place value (×100)
- Understand that the upper bead on the hundreds rod = 500
- Build any number from 100 to 999 on the three-rod abacus
Let's Learn
What you will learn today
Extend place value to the hundreds rod and build any 3-digit number on the abacus.
Welcome to Level 3! You already know two rods — tens and ones. Now you add a third rod to the left: the hundreds rod. With three rods, you can show any number from 1 to 999. Let's explore it.
The three-rod place value system
On a three-rod abacus, each rod has a value ten times bigger than the rod to its right:
- Rightmost rod = Ones (×1): shows 0–9
- Middle rod = Tens (×10): each lower bead = 10, upper bead = 50
- Leftmost rod = Hundreds (×100): each lower bead = 100, upper bead = 500
📐 How to show 100
Hundreds rod: 1 lower bead up = 100. Tens rod: clear = 0. Ones rod: clear = 0. Total: 100.
📐 How to show 347
Hundreds: 3 lower beads (= 300). Tens: 4 lower beads (= 40). Ones: upper bead + 2 lower beads (= 7). Total: 300 + 40 + 7 = 347.
📐 How to show 509
Hundreds: upper bead (= 500). Tens: clear = 0. Ones: upper bead + 4 lower beads (= 9). Total: 500 + 0 + 9 = 509.
📐 How to show 615
Hundreds: upper bead + 1 lower bead (= 600 + 100? No — wait). Let's count: upper bead on hundreds = 500. 1 lower bead on hundreds = 100. Together: 600. Tens: 1 lower bead = 10. Ones: upper bead = 5. Total: 600 + 10 + 5 = 615.
Reading a three-rod number — always left to right
Read hundreds first, then tens, then ones — exactly how we write numbers. Hundreds rod on the left = the biggest value. Ones rod on the right = the smallest.
Upper bead on hundreds rod
The upper bead on the hundreds rod is worth 500 (not 50, not 5). Each rod multiplies the upper bead value by ten. Ones upper = 5. Tens upper = 50. Hundreds upper = 500.
Show 231
Build the number 231 on the three-rod abacus.
🎯 Goal: Show the number 231
Show 408
Build 408 on the three-rod abacus.
🎯 Goal: Show the number 408
Challenge Round
Show 762
Build 762 on the three-rod abacus. This uses the upper bead on the hundreds rod!
🎯 Goal: Show the number 762
You can now show any number from 1 to 999 on three rods! Hundreds on the left (×100), tens in the middle (×10), ones on the right (×1). You are ready to add and subtract with three-digit numbers.
↪ Next: Three-Digit Direct Addition — when no rules are needed.
Key Points
- ✓Hundreds rod (leftmost): each lower bead = 100, upper bead = 500
- ✓Three rods: hundreds × 100, tens × 10, ones × 1
- ✓Read left to right: hundreds → tens → ones
- ✓347 = 3 hundreds + 4 tens + 7 ones
- ✓Upper bead on hundreds = 500 (not 50 or 5)
Glossary
சொல் அகராதி
Hundreds rod
நூறுகள் தண்டு
Three digits
மூன்று இலக்கங்கள்
Place value
இட மதிப்பு
500
ஐந்நூறு
1 to 999
1 முதல் 999 வரை
Practice Activities
Read the Abacusஅபாகஸைப் படி
Look at each abacus and type the number it shows.
Look carefully at each abacus and type the number it shows.
Quizவினாடி வினா
Answer each question to check your understanding.
நூறுகள் தண்டில் 1 கீழ் மணியின் மதிப்பு என்ன?
What is the value of 1 lower bead on the hundreds rod?
Match the Termsபொருத்துக
Click a term on the left, then click its matching definition on the right.
Click a term, then click its matching definition.
Terms
Definitions
Fill in the Blanksஇடைவெளி நிரப்புக
Type the missing word and press Check or Enter.
Type the missing word and click Check or press Enter.