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? (b) Will the sum be greater than 8,50,000 or less than 8,50,000? Why do you think so? (c) Will the sum be greater than 8,83,128 or less than 8,83,128? Why do you think so? (d) Exact value of 4,63,128 + 4,19,682 = _____
Both estimates are correct. The sum is 8,82,810 which is more than 8,00,000 and less than 9,00,000. Estu's estimate (near 9,00,000) is closer because 9,00,000 - 8,82,810 = 17,190, while 8,82,810 - 8,00,000 = 82,810.
The sum will be greater than 8,50,000. We can estimate: 4,60,000 + 4,20,000 = 8,80,000 approximately, which is greater than 8,50,000.
The sum will be less than 8,83,128. The exact sum is 8,82,810 which is 318 less than 8,83,128.
8,82,810
Explanation
(a) The actual sum is 8,82,810. Comparing distances from estimates. (b) Rough estimation shows the sum will be around 8,80,000. (c) Calculate exact sum and compare. (d) Add the two numbers: 4,63,128 + 4,19,682 = 8,82,810