Question 1 - Page 50 - Prime Factorisation - Chapter 3 Class 7 - Finding Common Ground (Ganita Prakash II)

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Question 1 - Page 50 Is 2 × 2 × 7 = 28 a factor of 840? If yes, what should it be multiplied by to get 840? Let’s find Factors of 840 using Prime Factorisation So, we can write 840 = 2 × 2 × 2 × 3 × 5 × 7 Since in Prime Factorisation of 840, we have 2 × 2 × 7 Thus, 2 × 2 × 7 = 28 is a factor of 840 We need to find Number Multiplied by 28 to get 840 We can just multiply the numbers we didn’t use in the prime factorization Numbers used: 2, 2, 7 Numbers not used: 2, 3, 5 Thus, we multiply 2 × 3 × 5 = 30 So, we need to multiply 28 by 30 to get 840 Check: 28 × 30 = 840