S9fES  (exponent number)  ==>  integer
       (mantissa number)  ==>  integer

EXPONENT returns the exponent of NUMBER, if NUMBER is represented
by a floating point number internally. If it is an integer, it
return 0, indicating (* NUMBER (expt 10 0)).

MANTISSA returns the mantissa of NUMBER, if NUMBER is represented
by a floating point number internally. For integers, it returns
NUMBER.

(exponent 1.23e10)  ==>   8  ; 123.0e8
(exponent 0.0001)   ==>  -4  ; 1.0e-4
(exponent 123)      ==>   0

(mantissa 1.23e10)  ==>  123
(mantissa 0.0001)   ==>    1
(mantissa 123)      ==>  123
