Many people core apples and pears by cutting the fruit in quarters and then cutting the core out of each quarter. While this method works well enough, it's slow and results in awkwardly shaped pieces of fruit.
Here's a faster way of getting rid of the core; it's especially useful when you're dealing with lots of fruit. Note: If your recipe calls for peeling, do it before you slice.
1. Hold the fruit upright, try to judge where the core is, and slice off two opposite sides as close to the core as possible.
2. Rotate the fruit and slice off the two remaining sides to get a rectangular core piece and four flat-sided pieces of fruit (two wide and two narrow).