NCERT Class 7 Mathematics

(Ron) #1
308 MATHEMATICS


  1. (i) False; 10 × 10^11 = 10^12 and (100)^11 = 10^22 (ii) False; 2^3 = 8, 5^2 = 25
    (iii) False; 6^5 = 2^5 × 3^5 (iv) True; 3^0 = 1, (1000)^0 = 1

  2. (i) 28 × 3^4 (ii) 2 × 3^3 × 5 (iii) 3^6 × 2^6 (iv) 2^8 × 3 5. (i) 98 (ii)
    5t^4
    8 (iii) 1
    EXERCISE 13.3

  3. 279404 = 2 × 10^5 + 7 × 10^4 + 9 × 10^3 + 4 × 10^2 + 0 × 10^1 + 4 × 10^0
    3006194 = 3 × 10^6 + 0 × 10^5 + 0 × 10^4 + 6 × 10^3 + 1 × 10^2 + 9 × 10^1 + 4 × 10^0
    2806196 = 2 × 10^6 + 8 × 10^5 + 0 × 10^4 + 6 × 10^3 + 1 × 10^2 + 9 × 10^1 + 6 × 10^0
    120719 = 1 × 10^5 + 2 × 10^4 + 0 × 10^3 + 7 × 10^2 + 1 × 10^1 + 9 × 10^0
    20068 = 2 × 10^4 + 0 × 10^3 + 0 × 10^2 + 6 × 10^1 + 8 × 10^0

  4. (a) 86045 (b) 405302 (c) 30705 (d) 900230

  5. (i) 5 × 10^7 (ii) 7 × 10^6 (iii) 3.1865 × 10^9 (iv) 3.90878 × 10^5
    (v) 3.90878 × 10^4 (vi) 3.90878 × 10^3

  6. (a) 3.84 × 10^8 m (b) 3 × 10^8 m/s (c) 1.2756 × 10^7 m (d) 1.4 × 10^9 m
    (e) 1 × 10^11 (f) 1.2 × 10^10 years (g) 3 × 10^20 m (h) 6.023 × 10^22
    (i) 1.353 × 10^9 km^3 (j) 1.027 × 10^9


EXERCISE 14.1






(a) (b) (c)

(d) (e) (f)
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