Quantity or value used when an exact value is not necessary, relevant, or possible to find, depending on the context.

An approximation by estimation, or estimation, is a value that we determine to be sufficiently close to a real value that is observable but difficult to measure without more appropriate conditions and a suitable measuring tool.

Estimation makes it possible to obtain an **estimate**, which is a value that is close to the target value with a fairly low risk of error. This estimation is generally not based on precise calculations.

### Examples

- When driving in a car along a straight highway, a passenger can estimate the distance that separates them from the next exit. This approximation by estimation is based on the person’s experience with distances expressed in an appropriate unit of measurement. Here, the unit is the kilometre.
- The same driver can make an approximation by estimation of the time required to reach a certain destination, based on the speed of the vehicle.
- Considering the dimensions of a warehouse, a business owner can make an approximation by estimation about the number of vehicles that can be parked there.
- Depending on road conditions such as traffic and weather conditions, a driver estimated that he would need 3 hours to get to the airport.
- A journalist estimated that the crowd at a peaceful demonstration included about 50 000 people.

### Educational Note

An approximation by estimation is a process that makes it possible to find and use a value that is close to a real value, with a fairly low risk of error, but the quality of a good estimate depends on the data in the context where it operates as well as the experience that we have with similar situations, the validation of previous estimates, and the use of effective mental processes.