Estimation is the process of making an educated guess or an approximate prediction of the value, number or quantity of the material or objects in question. The estimation process depends on rounding the values up or down in order to facilitate working with the numbers. Approximation can be applied to quantities and measurements, calculations and solving problems.
Estimation

Approximation or estimation applies primarily to problems dealing with quantities and measurements. The estimation process has a practical use in finding solutions to realworld problems. If the problem is to estimate the amount of paint needed to cover the house, a wise approximation overestimates the number of gallons required for the project to ensure that there will be enough paint to do the job.
Practical Estimation

In reallife situations, estimation can be critical in saving money and time. Shoppers use it in determining the unit cost of items and running a continuous tally of the items to be purchased. There is no need to know exactly what the cost is. The shopper only wants to know if he has enough cash to pay for it. A ballpark figure is an adequate guess of the total cost and can ensure that there are no budget overruns.
Mathematics and Estimation

Rounding numbers is a handy tool for estimating and manipulating numerical values. When working with large numbers, rounding up to the nearest 10 allows the number 97 to be represented as 100. Rounding down allows 94 to be represented as 90.
Consistency is important in problem solving. If the decision is to round up, each number should be rounded up to the nearest 10, and the predicted value will overestimate the actual solution. If rounding down, be sure that all the numbers are rounded down and expect the proposed value to be less than the actual calculation. Mixing the rounding values usually leads to a misrepresentation of the predicted solution.
The Calculator and Estimation

Approximating the answer or estimating the predicted results of a problem saves time and reduces the chances of mistakes in problem solving. The calculator is useful in obtaining desired answers quickly, but it is not infallible. The user can make mistakes in entering numerical values, especially in long, tedious problems. Estimating the solution has value in determining if the calculator returned a reasonable answer.
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