The eggs that ship

Problem

At the farm, eggs are packed in cartons of per_box eggs, and a carton only ships if it's full. The ones that don't fill a carton stay behind. Write a function that takes how many eggs there are and how many fit in a carton, and returns how many eggs ship out, not how many cartons:

26 eggs at 12 per carton ship as 24. If not even one carton fills up, nothing ships.

Examples

• 26, 12 → 24

• Past the halfway mark

  22, 12 → 12

• Full cartons

  24, 12 → 24

• Not one full carton

  5, 12 → 0

Besides these, the challenge has hidden tests that are revealed when you submit your solution.

You start with this

def packed(eggs, per_box):
    pass

function packed(eggs, perBox) {
}