Chapter 1: Knowing Our Numbers – Exercise 1.1

Question: 1

Write each of the following in numeral form :

i) Eight thousand twelve

ii) Seventy thousand fifty-three

iii) Five lakh seven thousand four hundred six

iv) Six lakh tow thousand nine

v) Thirty lakh eleven thousand one

vi) Eight crore four lakh twenty-five.

vii) Three crore three thousand three hundred three

viii) Seventeen crores sixty lakh thirty thousand fifty-seven.

Solution:

i) 8,012

ii) 70,053

iii) 5,07,406

iv) 6,02,009

v) 30,11,001

vi) 8,04,00,025

vii) 3,03,03,303

viii) 17,60,30,057

Question: 2

Write the following numbers in words in the Indian system of numeration.

i) 42,007

ii) 4,05,045

iii) 35,42,012

iv) 7,06,04,014

v) 25,05,05,500

vi) 5,50,50,050

vii) 5,03,04,012

Solution:

i) Forty two thousand seven.

ii) Four lakh five thousand forty five.

iii) Thirty five lakh forty two thousand twelve.

iv) Seven crore six lakh four thousand fourteen.

v) Twenty five crore five lakh five thousand five hundred.

vi) Five crore fifty lakh fifty thousand fifty.

vii) Five crore three lakh four thousand twelve.

Question: 3

Insert commas in the correct positions to separate periods and write the following numbers in words:

i) 4375

ii) 24798

iii) 857367

iv) 9050784

v) 10105607

vi) 10000007

vii) 910107104

Solution:

i) 4,357

ii) 24,798

iii) 8,57,367

iv) 90,50,784

v) 1,01,05,607

vi) 1,00,00,007

vii) 91,01,07,104

Question: 4

Write each of the following in expanded form:

i) 3057

ii) 12345

iii) 10205

iv) 235060

Solution:

i) 3000 + 50 + 7

ii) 10000 + 2000 + 300 + 40 + 5

iii) 10000 + 200 + 5

iv) 200000 + 30000 + 5000 + 60

Question: 5

Write the corresponding numeral for each of the following :

i) 7 x 10000 + 2 x 1000 + 5 x 100 + 9 x 10 + 6 x 1

ii) 4 x 100000 + 5 x 1000 + 1 x 100 + 7 x 1

iii) 8 x 1000000 + 3 x 1000 + 6 x 1

iv) 5 x 10000000 + 7 x 1000000 + 8 x 1000 + 9 x 10 + 4

Solution:

i) 70000 + 2000 + 500 + 90 + 6 = 72,596

ii) 400000 + 5000 + 100 + 7 = 4,05,107

iii) 8000000 + 3000 + 6 = 80,03,006

iv) 50000000 + 7000000 + 8000 + 90 + 4 = 5,70,08,094

Question: 6

Find the place value of the digit 4 in each of the following:

i) 74983160

ii) 8745836

Solution:

i)  Place value of 4 = 4 × 10,00,00 = 40,00,00

ii) Place value of 4 = 4 × 10,000 = 40,000

Question: 7

Determine the product of the place values of two fives in 450758.

Solution:

Place value of first 5 = 5 × 10 = 50

Place value of second 5 = 5 × 10,000 = 50,000

Required product = 50 × 50,000 = 25, 00,000

Question: 8

Determine the difference of the place values of 7’s in 257839705.

Solution:

Place value of first 7 = 7 × 10 = 700

Place value of second 7 = 7 × 10,000 = 70, 00,000

Required difference = 70, 00,000 – 700 = 69, 99,300

Question: 9

Determine the difference between the place value and the face value of 5 in 78654321.

Solution:

The number = 7, 86, 54, 321

The place value of 5 = 5 ten thousands = 50,000

The face value of 5 = 5

Therefore, the difference = 50,000 – 5 = 49,995

Question: 10

Which digits have the same face value and place value in 92078634?

Solution:

The place value of a digit depends on the place where it occurs, while the face value is the value of the digit itself.

In a number, the digits that have same face value and place value are the ones digit and all the zeroes of the number.

Therefore, in 9, 20, 78,634, 4 ( the ones digit ) and 0 ( the lakhs digit ) have the same face value and place value

Question: 11

How many different 3- digit numbers can be formed by using the digits 0, 2, 5 without repeating any digit in the number?

Solution:

The three-digit numbers formed using the digits 0, 2 and 5 ( without repeating any digit in the number ) are 250 , 205 , 502 and 520.

Therefore, four such numbers can be formed.

Question: 12

Write all possible 3- digit numbers using 6, 0, 4 when

i) Repetition of digits is not allowed

ii) Repetition of digits is allowed

Solution:

i) 604, 640, 460, 406

ii) 666, 664, 646, 660, 606, 600, 644, 640, 604, 444, 466, 440, 446,464, 400, 404, 406, 460

Question: 13

Fill in the blanks:

i)1 Iakh = —— ten thousand

ii) 1 Iakh = —— thousand

iii) 1 Iakh = ——- hundred

iv) 1 Iakh = ——- ten

v) 1 crore = —– ten Iakh

vi) 1 crore = —– Iakh

vii)1 crore = —— ten thousand

viii) 1 crore = ——- thousand

ix) 1 crore = ——- hundred

x) 1 crore = —— ten

Solution:

i) 1 Iakh = 10 ten thousand

ii) 1 Iakh = 100 thousand

iii) 1 Iakh = 1000 hundred

iv) 1 Iakh = 10000 ten

v) 1 crore = 10 ten Iakh

vi) 1 crore = 100 Iakh

vii) 1 crore = 1000 ten thousand

viii) 1 crore = 10000 thousand

ix) 1 crore = 100000 hundred

x) 1 crore = 1000000 ten