For the following numbers, (i) use a calculator to add; and (ii) estimate the sum by rounding the numbers to the nearest ten-thousand and adding. 82,137
38,603
10,151
32,607
+
54,072
¯¯¯¯¯¯

Question

Quizplus · Accepted Answer

(i) To add the numbers using a calculator, simply input them and press the "+" button. The sum is 217,570.
(ii) To estimate the sum, round each number to the nearest ten-thousand: 
82,140
38,600
10,150
32,610
+
54,070
¯¯¯¯¯¯
Then add the rounded numbers: 
82,140
38,600
10,150
32,610
54,070
¯¯¯¯¯¯
217,570
The estimated sum is also 217,570. 
Comparing our estimated sum and the sum calculated using a calculator, we can see that choice (C) is the best option as it has both the closest estimated sum and calculated sum.

For the Following Numbers, (I) Use a Calculator to Add;