Estimation.

A measurement such as 8.473 m may contain more detail than we need. Rounding chooses the nearest value at a stated level of detail, such as the nearest tenth of a metre.

First identify the digit you intend to keep. The next digit decides which neighbouring rounded value is nearer. Decimal places count from the decimal point; significant figures start at the first non-zero digit. These describe accuracy in different ways, especially for small numbers.

An estimate deliberately replaces awkward numbers with nearby simpler ones. Its purpose is to predict the approximate size of an answer or check whether a calculator result is plausible.

Round each input to the accuracy requested, often one significant figure, and write the simplified calculation before evaluating it. This shows how the estimate was made. Do not confuse this with calculating exactly first and then rounding the final answer.

The appropriate final accuracy depends on what the answer represents. A price usually needs cents, while a number of buses must be a whole number that provides enough seats.

Keep full working precision until the end, then choose rounding that makes sense in the situation. Sometimes this means rounding up rather than to the nearest integer. Always ask whether your final number can actually perform the job described by the question.

State the rounding accuracy before doing any work. If the task is an estimate, show the rounded inputs; if it is a final-answer rounding task, keep the original inputs during calculation.

Check whether trailing zeros communicate the requested accuracy. Then interpret the result in context: nearest, whole number, enough capacity, or a sensible money amount may require different final decisions.