How do I put a lot of images on a web page without putting them on so many times?

My class has been given a challenge by my chemistry teacher. Get him 1 mole of pennies. Now obviously, that's more pennies then are in circulation. But he never said anything about them being physical pennies. So my question is, how can I put a ton of images on a page without printing them billions of times. I don't care what language the response is in, I'll figure that part out. I just need a way. Thank you!