Question

I run this sql statement on Oracle 11g database

select round(79/3 + 87/3 + 86/6 + 95/6) from dual

and it returns 85

select round(79/3 + 87/3 + 86/6 + 95/6,1) from dual

returns 85.5

select round(85.5) from dual

returns a correct value 86

Does anyone know why the first SQL statement doesn’t return a correct value 86 but it rounds it down to 85 ??

Answer 1

If you do:

select 79/3 + 87/3 + 86/6 + 95/6 from dual;

Oracle will return 85.49999999999999999999999999999999999999, which when rounded to 0 decimal places is indeed 85. It’s an artifact of floating point arithmetic.