You are an employer. You have ten employees. Each month, each one of your ten employees gives you ten bags of gold. Each bag of gold has ten pieces of gold in it. Each piece of gold weighs one pound. One of your employees is cheating you by only putting nine pieces of gold in each of his ten bags of gold. You have a scale (not a balance, a scale), and you can only take one measurement from the scale, only one (1) reading. How can you tell which of the ten employees is cheating you by using this scale and only taking one measurement?
Take 1 bag from employee 1, 2 bags from employee 2, and so on up to 10 bags from employee 10.
Weigh them all. You should now know how many coins you are short.
If you are 1 coin short it is employee 1 that is the cheat. If you are 2 coins short then it's employee 2. And so on up to 10 coins short being employee 10.