That's how people write "raised to the power of" on this website.
7^2 means '7 squared'.
4^6 means '4 raised to the sixth power'.
(a+b+D)^3 means (a+b+D)-cubed.
This website does have a way to write actual exponents, but when you
use them, they're so tiny that you can't read them clearly, and it's easy
to mistake one exponent for a different one. Just one of the many, many,
. . . . . . . . . . . . . many, . . . . . . . . . . . . . . . little
problems with this website.