The problem of determining the densest possible packing of spheres originated from a 16th-century question about cannonball stacking.

How a 16th century pirate accidentally spawned a centuries-old math problem A question posed by Sir Walter Raleigh about cannonballs inadvertently led to a puzzle that mathematicians have been trying to solve for centuries https://www.scientificamerican.com/article/how-a-16th-century-pirate-accidentally-spawned-a-centuries-old-math-problem/

How a 16th century pirate accidentally spawned a centuries-old math problem During his expeditions, Raleigh’s ships carried cannonballs on board for protection against enemy attacks. He wanted to quickly know how many he had at a glance, so he presented his scientific advisor, Thomas Harriot, with a seemingly simple task: calculate the number of cannonballs stacked in a pile. Harriot quickly found a convenient formula for how many were arranged in a square pyramid based on the number in the bottom row and was able to present Raleigh with a satisfactory solution. But Harriot wondered whether that arrangement was truly the densest possible packing of spheres. What if there were an infinite number of cannonballs to consider? https://www.scientificamerican.com/article/how-a-16th-century-pirate-accidentally-spawned-a-centuries-old-math-problem/