What is a compatible number estimation?

A compatible number estimation is a technique used to simplify calculations by rounding numbers to values that are easier to work with, often whole numbers or numbers that are easy to divide. This approach makes mental math more manageable and helps provide a quick approximation of the actual answer. For example, when estimating the sum of 48 and 27, one might round 48 to 50 and 27 to 30, making it easier to compute a rough estimate of 80.