ORACLE - Conversion Functions : To_Number

The to_number function converts a string to a number.

The syntax is:
to_number( string1, [ format_mask ], [ nls_language ] )
string1 is the string that will be converted to a number.
format_mask is optional. This is the format that will be used to convert string1 to a number.
nls_language is optional. This is the nls language used to convert string1 to a number.

For example:
to_number('981.53', 9999.99') would return the number 981.53
to_number('225', '999') would return the number 225
to_number('23', '99') would return the number 23

Since the format_mask and nls_language parameters are optional, you can simply convert a text string to a numeric value as follows:
to_number('1210.73'') would return the number 1210.73