if a raised to the nth power is equal to x (a>0, and a is not equal to 1), then the number n is called the logarithm (logarithm) of x with a as the base, recorded as n=logax. among them, a is called the base of the logarithm, x is called the real number, and n is called the "logarithm of x with a as the base".

in b=lgn, the antilog is the known logarithm b to find the corresponding real number n, and 10^b=n, so n=lg-1b=10^b, just calculate 10^b directly.

the abbreviated notation [4; 2, 6, 7] can be obtained by removing the redundant part in the expression 4 + 1/(2 + 1/(6 + 1/7)).