Question 1061185
Your description is very poor.  If you are trying to show a formula for exponential decay for some radioactive gold, express it this way:
{{{A(t)=A[o]e^(-kt)}}}
which could be shown in pure text as  A(t)=A[o]e^(-kt).

<pre>
{{{A(t)}}}    Amount of the gold remaining after time t
t       Amount of time passage
{{{A[o]}}}    Initial amount of the gold when t=0
k       A constant to be determined or given
</pre>

If you are asking for a decay function, then that would be a good way to show it.   Nothing to "round" to any decimal places, because no values were given in description, none in the question, so nothing to be evaluated or computed.