What is 35 parts per thousand?

35 parts per thousand means you have 35 small pieces out of a total of 1,000 pieces.

Imagine you have a big bag of 1,000 jellybeans, that's like having a thousand jellybeans in your hand! Now, if 35 of those jellybeans are red, and the rest are blue or green, then 35 parts per thousand is how we describe the number of red jellybeans compared to all the jellybeans.

Think about a tiny sandwich, maybe you’re eating a snack with your friends. If your sandwich has 1,000 tiny pieces of bread and cheese, and 35 of them are extra special, like they have chocolate on them, then that’s 35 parts per thousand of chocolatey goodness in your sandwich.

It's a way to say how much of something there is compared to the whole bunch. Just like how many red jellybeans you have out of 1,000 or how many chocolate slices are in your tiny sandwich!