Of Crores and Crores!

Class 7 Maths · Chapter 1: Large Numbers Around Us · NCERT Ganita Prakash section 1.3

Learn

Press +10,00,000 (ten lakh) ten times and you get 100 lakh, which is one crore: 1,00,00,000, 1 followed by 7 zeros. A hundred crore is one arab: 1,00,00,00,000 (9 zeros). Each step is 100 times the one before: 100 thousand = 1 lakh, 100 lakh = 1 crore, 100 crore = 1 arab.

1 crore = 1,00,00,000 (7 zeros)

Two systems. The Indian system groups digits 3-2-2-2… from the right: thousand, lakh, crore, arab. The American (International) system groups 3-3-3…: thousand, million, billion. The same number 9876501234 is 9,87,65,01,234 (Indian) and 9,876,501,234 (American).

9,87,65,01,234 = 9,876,501,234

Converting: 10 lakh = 1 million (1,000,000), 1 crore = 10 million, 10 crore = 100 million, 100 crore (1 arab) = 1 billion. The words lakh and crore come from Sanskrit lakṣha and koṭi, and the Indian system is used in several neighbouring countries too.

10 lakh = 1 million · 100 crore = 1 billion

Reading a big number: first place the commas. 4050678 → 40,50,678 = forty lakh fifty thousand six hundred seventy eight; in the American system 4,050,678 = four million fifty thousand six hundred seventy eight. To compare across systems, change both to one system: 500 lakh = 5 crore = 50 million, so 500 lakh > 5 million.

Explore: Indian or American commas?

1. Sort each number by its comma pattern.

Remember

• 1 lakh = 5 zeros, 1 crore = 7 zeros, 1 arab = 9 zeros; 1 million = 6 zeros, 1 billion = 9 zeros.
• Indian commas 3-2-2-…, American 3-3-3-…; 10 lakh = 1 million, 100 crore = 1 billion.

Quick check

How many million make 1 crore?

1. 10
2. 1
3. 100
4. 1,000

Think about it

How many lakhs make a billion?

Practice

Practise with fresh questions at three levels (easy, medium, hard), some answered hands-on, with hints and worked answers. Get 4 of your last 5 right to finish the topic.