1. the division is of two integers so the decimal places are lost. Add decimal points to the numbers like this:
2. The result is being rounded to the nearest decimal position.
99997./100000. = .99997
rounding that yields 1.000 which is correct. You either need more decimal places in the result or do it a different way, e.g.
SELECT left(CAST(99997./100000. AS varchar(18)), 5)
SELECT CAST(99997./100000. AS NUMERIC(18,5))