Uncategorized

  1. Math

    Coins for Making Change Efficiently

    The item I had just bought cost 29 cents. I gave the cashier a dollar bill, and she gave me two quarters, two dimes, and a penny in change. She could just as well have given me seven dimes and a penny or some other combination of coins adding up to 71 cents, but there’s […]

    By Ivars Peterson

  2. 19320

    This article could have been a little less disingenuous. It would still have been a very good article if you had used “sulfuric acid” instead of “odorless hydrogen sulfate” and admitted that the process still required a little alkali to neutralize this waste stream that is “carried away by water trickling over the foam.”