Recycling by product massive number of types of plastic, they each carry a resin identification code, and must be sorted before they can be recycled. This can be costly; while metals can be sorted using electromagnets, no such 'easy sorting' capability exists for plastics. In addition to this, while labels do not need to be removed from bottles for recycling, lids are often made from a different kind of non-recyclable plastic. To help in identifying the materials in various plastic items, resin identification code numbers 1-6 have been assigned to six common kinds of recyclable plastic resins, with the number 7 indicating any
National identification number "Birth Number" (Slovak: "Rodné číslo" (RČ)), issued at birth by the civic records authority (Slovak: "matrika") and recorded on the birth certificate. Its format is YYMMDD/XXXX with YYMMDD being the date of birth and XXXX being a semi-unique identifier. For females, the month of the date of birth is advanced by 50. Full identification number in the form YYMMDDXXXX must be divisible by 11. Since this system does not provide a truly unique identifier (the numbers are repeated every century) and contains what might be considered private information, it may be updated in the future. The second system is the