10 முதல் 20 வரை கட்டுவோம்
Building Numbers 10 to 20
Now use both rods together! Build every number from 10 to 20 step by step and learn to read two-rod numbers quickly.
Let's Learn
What you will learn today
Build every number from 10 to 20 on the abacus using the tens and ones rods.
You know place value. Now let's build real two-digit numbers! All numbers from 10 to 19 follow the same pattern: 1 bead on the tens rod (that gives 10) plus the ones digit on the ones rod.
Quick recap
You know place value: the rightmost rod = ones (×1), the next rod left = tens (×10). Now let's put that to work for every number from 10 to 20.
Teen numbers — the pattern
All numbers from 10 to 19 have exactly 1 lower bead on the tens rod. That gives 10. Then the ones rod shows the ones digit using the same rules you already know.
📐 10 — one ten, no ones
Tens rod: 1 lower bead = 10. Ones rod: clear = 0. Total: 10.
📐 13 — one ten and three ones
Tens rod: 1 lower bead = 10. Ones rod: 3 lower beads = 3. Total: 13.
📐 15 — one ten and five
Tens rod: 1 lower bead = 10. Ones rod: upper bead down = 5. Total: 15. The upper bead appears on the ones rod now!
📐 19 — one ten and nine
Tens rod: 1 lower bead = 10. Ones rod: upper bead + 4 lower beads = 9. Total: 19.
📐 20 — two tens, no ones
Tens rod: 2 lower beads = 20. Ones rod: clear = 0. Total: 20. Now the tens rod shows 2!
Teen numbers — tens rod always shows 1
For 10 to 19: the tens rod ALWAYS has exactly 1 bead. Only the ones rod changes. Once you hit 20, the tens rod shows 2.
Forgetting the ones rod
When building teen numbers, children sometimes only set the tens rod and forget the ones rod. For 13: you need BOTH 1 on the tens rod AND 3 on the ones rod. Always set both rods.
Show 17
Show the number 17 on the two-rod abacus.
🎯 Goal: Show the number 17
Now try 14
Show the number 14 on the two-rod abacus.
🎯 Goal: Show the number 14
Challenge Round
Show 18
Build 18 on the two-rod abacus. This one needs the upper bead on the ones rod!
🎯 Goal: Show the number 18
You can now build any number from 10 to 20! Teen numbers: 1 ten on the tens rod, plus the ones digit on the ones rod. This is real two-digit number work! Next we start adding on the abacus.
↪ Next: Simple Addition — Within 5
Key Points
முக்கிய குறிப்புகள்
- ✓10 = 1 bead on tens rod, 0 on ones rod
- ✓11 = 1 bead on tens rod, 1 bead on ones rod
- ✓15 = 1 bead on tens rod, upper bead on ones rod
- ✓19 = 1 bead on tens rod, upper bead + 4 lower beads on ones rod
- ✓20 = 2 beads on tens rod, 0 on ones rod
Lesson Materialsபாட வளங்கள்
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Glossary
சொல் அகராதி
Teen numbers
பதின்ம எண்கள்
10
பத்து
15
பதினைந்து
20
இருபது
Two rods
இரண்டு தண்டுகள்
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.
அபாகஸில் 12 காட்ட எந்த தண்டுகளை பயன்படுத்துவீர்கள்?
To show 12 on the abacus, which rods do you use?
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.