Turns out that $10 in quarters weighs half a pound. Which means one pound of quarters (which individually weigh 5.67g), naturally, adds up to $20. Handy, I thought. Looking at the United States Mint's coin specifications page, I learned that, at 2.268g per dime, one pound of dimes also equals $20.
What are the weights of US coins?
To test a digital scale if you don't have a special calibration weight you can use coins: (Make sure to use new, shiny coins. Worn coins will weigh less). A U.S. nickel (5-cent coin for non-Americans) weighs exactly 5.00 grams and a U.S. cent (since 1983) weighs exactly 2.50 grams.