Hinglish

A Lakh Varieties!

Class 7 Maths · Chapter 1: Large Numbers Around Us · NCERT Ganita Prakash section 1.1

Learn

Meher's grandfather keeps a seed bank in his village: little cloth bags of seeds from many kinds of millets and pulses. "Long ago," he says, "farmers in our country grew lakhs of different crop varieties." Meher wonders: just how big is one lakh?

Follow the pattern. The largest 3-digit number is 999; add 1 and you get the smallest 4-digit number, 1,000. The largest 4-digit number is 9,999; add 1 → 10,000. The largest 5-digit number is 99,999; add 1 → 1,00,000, the smallest 6-digit number. We read it as one lakh.

99,999 + 1 = 1,00,000 (one lakh)

Is a lakh big or small? It depends on what you compare it with. One lakh days is about 274 years, longer than any human life (365 × 274 = 1,00,010). But a big cricket stadium can seat more than a lakh people, and a person's head has about a lakh hairs in a tiny space!

365 × 274 = 1,00,010 days ≈ 1 lakh

Reading and writing: in the Indian system we put a comma after the thousands group and then after every two digits: 12,78,830 is read twelve lakh seventy eight thousand eight hundred thirty. Going the other way, "fifty lakh five thousand fifty" is 50,05,050: zeros keep the empty places.

50,05,050 = 50 lakh + 5 thousand + 50

Explore: make numbers on the digit wheels.

  1. Make one lakh.
  2. Make the largest 5-digit number (you can keep the first wheel at 0).
  3. Make fifty lakh five thousand fifty.
  4. Make ten lakh two hundred thirty five.

Remember

  • 1,00,000 (one lakh) is the smallest 6-digit number: 99,999 + 1.
  • Indian commas: after the thousands group, then every two digits (12,78,830).

Quick check

Which is the smallest 6-digit number?

  1. 1,00,000
  2. 99,999
  3. 10,000
  4. 1,00,001
Answer

1,00,000. 99,999 + 1 = 1,00,000, one lakh.

Think about it

Is one lakh rupees a lot of money? Give one reason why it is, and one why it is not.

One answer

It is a lot for buying a bicycle (it could buy dozens!), but not much for buying a house in a city, which can cost many lakhs. Whether a number is big depends on what we compare it with.

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.