Concept 3 of 7
The International System: Millions & Billions
Today's big idea
International grouping runs in threes: ones, thousands, millions, then billions.
One million is ten lakh and one billion a hundred crore, not one of each.
How it works
👀 What's going on?
A news site says a company raised fifty million dollars and you have no instant sense of how big that is. The number is not the problem. The grouping it arrives in is unfamiliar.
💡 Here's the trick
Look at the number above. The international system groups in threes the whole way: ones, thousands, millions, then billions. Nothing else changes, so a number is the same size in both systems and only the commas and the names move.
🪄 How to do it
- 1.Mark off the number above in threes from the right.
- 2.Name the groups outwards: thousands, millions, then billions.
- 3.To convert, rewrite the same digits under the other system's commas.
✍️ Try it
Write 7,50,00,000 in the international system. Then: how many crores are there in one billion?
The same digits regrouped in threes give 75,000,000, read as seventy-five million. One billion is 1,000,000,000, which regrouped is 100,00,00,000, so it is 100 crore.
⚠️ Watch out
You might be thinking a million matches a lakh and a billion matches a crore. They do not. One million is ten lakh and one billion is a hundred crore. A headline in millions is always ten times what the word lakh would suggest.
🌟 Why this matters
Anything you read from outside India, from app downloads to company funding, arrives in millions and billions. Converting quickly stops the number being meaningless.
Exam tip: Learn the two anchors, one million is ten lakh and one billion is a hundred crore, and the rest follows.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“An American newspaper writes 250 million. How many lakh is that?”
- 1
Recall the bridge
1 million = 10 lakh. 🌍
- 2
Multiply across
250 × 10 = 2,500
- 3
Add the unit
250 million = 2,500 lakh.
- 4
Answer ✓
250 million = 2,500 lakh (= 25 crore)
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Tap the gaps to drop commas. International system: groups of 3 — thousand, million, billion.
GROUP IN THREES · ROUND 1 OF 3
Tap the dots to add commas.
Quick check
✅ VERIFICATION
How is 60,00,000 (sixty lakh) written in the international system?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Reading & Writing Large Numbers
Read period-by-period, don't lose the zeros.