maths

a^-1 = 10
(a^-1)^-1 = (10)^-1
a^1 = 1/10 or just a = 1/10
raising a number to a negative exponent means you are inverting it by switching the numerator and denominator.
10 is the same as 10/1 so 10^-1 is the inverse of 10/1 (equals 1/10)