You should better take out that money and put them in your pocket. That would make more sense.

Talking about investing those 6$ to gambling, like multipliers, yes, it might look like a fast way to earn a decent amount of money, but everything that is easy and fast, always has a catch. I dont really know anyone who would have made profit in a long term from investing to gambling. Sooner or later your luck ends and you loose your dollars. You could try speculating with them, buying bitcoins for a lower price and selling for higher, as the market of bitcoins these days seems to be rapidly changing, but its risky. If you want to make profit from what you have, and you want it to be a fast profit, you will definitely have to risk, but as I said, you better buy for them something useful.