Issue

You can observe the phenomenon where mathematically identical formulas return different results when applying ROUND as follows.

SQL> select round(8003/60*30,0) from dual ;
ROUND(8003/60*30,0)
-------------------
               4001

SQL> select round(8003*30/60,0) from dual ;
ROUND(8003*30/60,0)
-------------------
               4002

Cause

The final ROUND result value differs depending on the order of operations.

Solutions

Since calculation results for sensitive data (amounts, quantities) can differ, it is recommended to apply the following workarounds and rules.

• Perform multiplication first, then division as a standard coding rule, leading with integer multiplication before inducing division.
• Explicitly apply ROUND/TRUNC to intermediate results to strictly control decimal places.

• Preserve decimal points as much as possible to induce the desired rounding after rounding.

  SQL> select round(round(8003/60*30,20), 0) from dual ;
  ROUND(ROUND(8003/60*30,20),0)
  -----------------------------
                           4002
  
  SQL> select round(8003*30/60,0) from dual ;
  ROUND(8003*30/60,0)
  -------------------
                 4002