An approximation is a close estimate that's near the true answer but not exactly perfect. When you round 3.7 to 4, or estimate that 48 plus 51 equals about 100, you're making an approximation.

Scientists and engineers use approximations constantly because getting perfectly exact answers is often impossible or unnecessary. A carpenter might approximate the amount of wood needed for a project, knowing they can adjust as they build. A chef approximates measurements when a recipe calls for “about a cup” of flour. When you estimate how long it will take to walk to school, you're making an approximation based on past experience.

Sometimes approximations are quite rough, like guessing there are “around 200” students in your grade. Other times they're remarkably precise, like when scientists calculate pi to 3.14159, knowing the decimals continue forever but stopping when they have enough accuracy.

Understanding when approximations are good enough and when you need exact numbers is an important skill. You can approximate your friend's height, but a doctor needs precise measurements. The art is knowing which situations call for which approach.