Obtain an estimate for the fallen competition by rounding a number so that the resulting arithmetic can easily be performed by hand or in head. Then, use a calculator to perform the computation. How reasonable is your estimate when compared to the actual answer?
319 + 579
Round the two numbers to the nearest 10. An estimate of the sum is?

From the question, we are told that to find the sum of the two values 319 + 579, but we are to first convert this two numbers to nearest 10 before estimating the sum.

Step 1: Converting 319 and 579 to nearest 10

To convert to nearest tgen means we are to have just one zero at the end of the number. To do this we will check if the last digit of the value is more than 5, if it is we will round up the value preceding the last number by adding 1 to it but if the last digit of the value is not up to 5, will round not up the value preceding the last number.

For 319 to nearest 10 is 320 while 579 to nearest 10 is 580. Note that the last value which is 9 is more than 1, hence the reason for the approximation.

Step 2: Taking the sum of the numbers approximated;

320 + 580

= 900

Sum of the numbers without rounding up is 319+579 = 898

The estimate of the real figure (900) when compared to the actual answer (898) is reasonable because the difference in both value is 2 which is not too significant.