It's T-Shirt Tuesday!

Every week on the day after Monday, we're releasing new shirt designs in the mental_floss store. Today, it's Factorials (above). They say a team is just the sum of its parts. But this team, the Factorials, is the Product of its parts—each of them adding to ... errrr, multiplying the value of the entire team.
If you're not a math genius, don't sweat it—we sell literary t-shirts, too!
Today only, you can get free shipping on all orders in the mental_floss store! Just enter the code TUESFREE at checkout; free shipping ends at midnight PST.
Did you know that you can submit t-shirt slogans? Julia M. from Santa Barbara, California, came up with the Factorials idea. She gets $125, a free shirt, and eternal "I designed a mental_floss t-shirt!" bragging rights. If you have a funny t-shirt slogan, you can submit it here.