NCERT Solutions Ganita Prakash (Part 1) Chapter 1 .3 Of Crores and Crores! — Figure it Out

Book page 91 Updated on2026-09-05

Q1.

Read the following numbers in Indian place value notation and write their number names in both the Indian and American systems: (a) 4050678 (b) 48121620 (c) 20022002 (d) 246813579 (e) 345000543 (f) 1020304050

Answer

Place the commas first — 3-2-2-2 from the right for the Indian system, 3-3-3 for the American system.

Number	Indian system	American system
(a) 4050678	40,50,678 Forty lakh fifty thousand six hundred seventy eight	4,050,678 Four million fifty thousand six hundred seventy eight
(b) 48121620	4,81,21,620 Four crore eighty one lakh twenty one thousand six hundred twenty	48,121,620 Forty eight million one hundred twenty one thousand six hundred twenty
(c) 20022002	2,00,22,002 Two crore twenty two thousand two	20,022,002 Twenty million twenty two thousand two
(d) 246813579	24,68,13,579 Twenty four crore sixty eight lakh thirteen thousand five hundred seventy nine	246,813,579 Two hundred forty six million eight hundred thirteen thousand five hundred seventy nine
(e) 345000543	34,50,00,543 Thirty four crore fifty lakh five hundred forty three	345,000,543 Three hundred forty five million five hundred forty three
(f) 1020304050	1,02,03,04,050 One arab two crore three lakh four thousand fifty	1,020,304,050 One billion twenty million three hundred four thousand fifty

Why it happens: The digits never change — only the grouping does. In (c) the Indian grouping 2,00,22,002 shows “two crore, zero lakh, twenty two thousand, two”, and the zero lakh group is simply not read aloud.

Tip: A quick check — an Indian-system number with 8 digits is in crores; with 9 digits it is in ten-crores; with 10 digits it is in arabs.

Q2.

Write the following numbers in Indian place value notation: (a) One crore one lakh one thousand ten (b) One billion one million one thousand one (c) Ten crore twenty lakh thirty thousand forty (d) Nine billion eighty million seven hundred thousand six hundred

Answer

For (b) and (d), first build the number in the American system, then re-comma it the Indian way.

Number name	Indian place value notation
(a) One crore one lakh one thousand ten	1,01,01,010
(b) One billion one million one thousand one	1,00,10,01,001
(c) Ten crore twenty lakh thirty thousand forty	10,20,30,040
(d) Nine billion eighty million seven hundred thousand six hundred	9,08,07,00,600

(b) 1 billion = 1,000,000,000
1 million = 1,000,000
1 thousand = 1,000, and one = 1
Total = 1,001,001,001
Indian commas → 1,00,10,01,001

(d) 9,000,000,000 + 80,000,000 + 700,000 + 600
= 9,080,700,600
Indian commas → 9,08,07,00,600

Why it happens: Both systems write the same digits; only the comma pattern differs. Write the digits once without any commas, then insert commas from the right — 3, then 2, 2, 2 for the Indian system.

Q3.

Compare and write ‘<’, ‘>’ or ‘=’: (a) 30 thousand ____ 3 lakhs (b) 500 lakhs ______ 5 million (c) 800 thousand ____ 8 million (d) 640 crore ______ 60 billion

Answer

Bring both sides into plain digits first, then compare.

Comparison	Left in digits	Right in digits	Sign
(a) 30 thousand ? 3 lakhs	30,000	3,00,000	<
(b) 500 lakhs ? 5 million	5,00,00,000	50,00,000	>
(c) 800 thousand ? 8 million	8,00,000	80,00,000	<
(d) 640 crore ? 60 billion	6,40,00,00,000	60,00,00,00,000	<

(b) 500 lakhs = 500 × 1,00,000 = 5,00,00,000 (5 crore)
5 million = 5 × 10,00,000 = 50,00,000 (50 lakh)
5 crore is ten times 50 lakh, so 500 lakhs > 5 million

(d) 640 crore = 640 × 1,00,00,000 = 6.4 × 10⁹ = 6.4 billion
60 billion = 60 × 10⁹
6.4 billion < 60 billion, so 640 crore < 60 billion

Why it happens: The safest method is to count digits. 6,40,00,00,000 has 10 digits while 60,00,00,00,000 has 11 — more digits always means a bigger whole number.

Tip: Two conversions worth memorising: 1 million = 10 lakh and 1 billion = 100 crore.

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