Skip counting is a useful skill if you need to count sets of objects, such as pairs of shoes, gloves, the wheels on a tricycle, or even money. Counting on in twos, threes, fives and tens is easy, if ...

This year, NMNH director Kirk Johnson helped spearhead an effort to add up the collections of the world’s largest museums Jack Tamisiea A small fraction of the more than 50 million specimens housed in ...