what do you mean with "pow" ? only exponents formed by "4"s (like "4^SQRT(4)"), or any power, like 4^0? Then it'l be 4!*SQRT(4)+4-4^0

If any "Function" is allowed, one could do the following

51 = "LEFT"((4^4*SQRT(4)),SQRT(4))

which is "LEFT"(512,2)

which is 51

but I'm sure, that's illegal ...