Chapter 1: Knowing Our Numbers – Exercise 1.7
Question: 1
Estimate the following by rounding off each factor to nearest hundreds:
i) 730 + 998
ii) 796 – 314
iii) 875 – 384
Solution:
i) 700 + 1000 = 1700
ii) 800 – 300 = 500
iii) 900 – 400 = 500
Question: 2
Estimate the following by rounding off each factor to nearest thousands:
i) 12904 + 2888
ii) 28292 – 21496
Solution:
i) 13000 + 3000 = 16000
ii) 28000 – 21000 = 7000
Question: 3
Estimate the following by rounding off each number to its greatest place:
i) 439 + 334 + 4317
ii) 8325 – 491
iii) 108734 – 47599
iv) 898 × 785
v) 9 × 795
vi) 87 × 317
Solution:
i) 400 + 300 + 4000 = 4700
ii)8000 – 500 = 7500
iii)100000 -500000 = 50000
iv) 900 × 800 = 720000
v) 10 × 800 = 8000
vi) 90 x 300 = 27000
Question: 4
Find the estimated quotient for each of the following by rounding off each number to its greatest place :
i) 878 ÷ 28
ii) 745 ÷ 24
iii) 4489 ÷ 394
Solution:
i) 900 ÷ 30 = 30
ii) 700 ÷ 20 = 35
iii) 4000 ÷ 400 = 10
Question: 5
Write the expression for each of the following statements using brackets:
i) Four multiplied by the sum of 13 and 7
ii) Eight multiplied by the difference of four from nine.
iii) Divide the difference of twenty eight and seven by 3.
The sum of 3 and 7 in multiplied by the difference of twelve and eight.
Solution:
i) 4 × (13 + 7)
ii) 8 × (9 – 4)
iii) 28 – 73
iv) (3 + 7) x (12 – 8)
Question: 6
Simplify each of the following:
i) 124 – (12 – 2) × 9
ii) (13 + 7) × (9 – 4) – 18
iii) 210 – (14 – 4) x (18 + 2) – 10
Solution:
i) 34
ii) 82
iii) 0
Question: 7
Simplify each of the following:
i) 7 × 109
ii) 6 × 112
iii) 9 × 105
iv) 17 × 109
v) 16 × 108
vi) 12 × 105
vii) 102 × 103
viii) 101 × 105
ix) 109 × 107
Solution:
i) 763
ii) 672
iii) 945
iv) 1853
v) 1728
vi) 1260
vii) 10506
viii)10605
ix)11663
Question: 8
Write the roman – numerals for each of the following:
i) 33
ii) 48
iii) 76
iv) 95
Solution:
i) XXXIII
ii) XLVIII
iii) LXXVI
iv) XCV
Question: 9
Write the following in roman numerals:
i) 154
ii) 173
iii) 248
iv) 319
Solution:
i) CLIV
ii) CLXXIII
iii) CCXLVIII
iv) CCCXIX
Question: 10
Write the following in roman numerals:
i) 1008
ii) 2718
iii) 3906
iv) 3794
Solution:
i) KVIII
ii) KKDCCXVIII
iii) KKKCKVI
iv) KKKDCCXCIV
Question: 11
Write the following in roman numerals:
i) 4201
ii) 10009
iii) 44000
iv) 25819
Solution:
Question: 12
Write the following in Hindu – Arabic numerical:
i) XXVI
ii) XXIX
iii) LXXII
iv) XCI
Solution:
i) 26
ii) 29
iii) 72
iv) 91
Question: 13
Write the corresponding Hindu – Arabic numerical for each of the following:
i) CIX
ii) CLXXII
iii) CCLIV
iv) CCCXXIX
Solution:
i) 109
ii) 172
iii) 254
iv) 329
Question: 14
Write the corresponding Hindu – Arabic numerical for each of the following:
i) KXIX
ii) KDLXV
iii) KKCXXIII
iv) KKKDCXL
Solution:
i) 1019
ii) 1565
iii) 2123
iv) 3640
Question: 15
Write the following in Hindu – Arabic numerical:
Solution:
i) 4444
ii) 6949
iii) 9391
iv) 70009
Question: 16
Which of the following is meaningless?
ii) KKKCCXI
iii) XD
iv) VC
Solution:
(i) and (iii) are meaningless.