The INT function behaves a bit differently with negative values, so in this example we are using the TRUNC function. The TRUNC function simply truncates (i.e. removes) decimal values if they exist – it doesn't do any rounding.
In the example shown, cell C6 contains this formula:
The TRUNC function returns the integer portion of the number which is then subtracted from the original value. The result is the decimal portion of the number.
If the original number is an integer to begin with, the result of this formula is zero.