integer arithmetic

I'm getting weird results when I do integer division.

Frequency is being read in as 60 but the result being stored in var_1b /= 1e9/60 (~1.6E7). Instead the result reported by temp2 is 20522. The division for var_1a is performed correctly.

The offending code:

shared variable frequency: integer range 0 to 25000 :=0;

shared variable var_1a, var_1b, var_1c, var_1d: integer;

...

frequency := (to_integer(unsigned(Fin)));

var_1a := (1E9/pi_2);

var_1b := (1E9/(frequency));

temp <= std_logic_vector(to_unsigned(frequency, 16));

temp2 <= std_logic_vector(to_unsigned(var_1b, 16));