Oracle abs() function

ABS(n) - Return absolute value of number . This function will remove the minus sign and return it.

sqlplus >select abs(-12.55) from dual

result :
12.55

sqlplus >select abs(12.55) from dual

result :
12.55

Here is more advanced one .

select abs(-12)+10 from dual

result : 22

select abs(-12+10) from dual

result : 2