Question 1 (Page number 11) - Estimating value of expression (Page number 11) - Chapter 1 Class 7 - Large Numbers Around us (Ganita Prakash)

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Question 1 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 4,63,128 + 4,19,682 Roxie: “The sum is near 8,00,000 and is more than 8,00,000.” Estu: “The sum is near 9,00,000 and is less than 9,00,000.” (a) Are these estimates correct? Whose estimate is closer to the sum?For accurate estimates, we could round off numbers to nearest ten thousand or nearest thousand Let’s estimate nearest ten thousand For 4,63,128, we round down 63,128 to 63,000 ∴ 4,63,128 → 4,63,000 For 4,19,682 , we round up19,682 to 20,000 ∴ 4,19,682 → 4,20,000 Estimated sum = 4,63,000 + 4,20,000 = 8,83,000 Now, our statements are Roxie: “The sum is near 8,00,000 and is more than 8,00,000.” Estu: “The sum is near 9,00,000 and is less than 9,00,000.” Roxie said: >8,00,000 ✅ Correct Estu said: <9,00,000 ✅ Correct Both are correct, but Estu is closer, because 8,83,000 is closer to 9,00,000 than to 8,00,000. Question 1 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 4,63,128 + 4,19,682 Roxie: “The sum is near 8,00,000 and is more than 8,00,000.” Estu: “The sum is near 9,00,000 and is less than 9,00,000.” (b) Will the sum be greater than 8,50,000 or less than 8,50,000? Why do you think so? Our Estimated sum = 8,83,000 So, its greater than 8,50,0000 Question 1 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 4,63,128 + 4,19,682 Roxie: “The sum is near 8,00,000 and is more than 8,00,000.” Estu: “The sum is near 9,00,000 and is less than 9,00,000.” (c) Will the sum be greater than 8,83,128 or less than 8,83,128? Why do you think so? Our Estimated sum = 8,83,000 Since while estimating we rounded down and rounded up It is difficult to estimate if sum would be greater or less than 8,83,128 Question 1 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 4,63,128 + 4,19,682 Roxie: “The sum is near 8,00,000 and is more than 8,00,000.” Estu: “The sum is near 9,00,000 and is less than 9,00,000.” (d) Exact value of 4,63,128 + 4,19,682 = ___________ Sum = 4,63,128 + 4,19,682 = 8,82,810 Thus, sum is less than 8,83,128