TRUNC shortens a numeric expression to a specified number of decimal places.
NUMBER
TRUNC(n1 [, n2 ])
n1 is the numeric expression to be truncated.
n2 is the number of decimal places. A positive number truncates digits to the right of the decimal point, and a negative number replaces digits to the left of the decimal point. The default value is zero (0).
TRUNC(15.79) returns the value 15.
TRUNC(15.79, 1) returns the value 15.7.
TRUNC(15.79, -1) returns the value 10.