To some extent the word cards is a misnomer. Any word such as 'paper' would be adequate. Number papers would be just as useful a descriptor. Because number chits are useful they wear out quickly ~ hence cards are a better longer-term investment.
Number cards have numbers written ~ drawn ~ or printed on them. There is an infinity of numbers ~ number cards are usually limited to a set of the ten digits, or of the numerals up to 100.



Number cards can easily be made by hand or by using a home computer and printer (capable of handling card). All those shown ~ above ~ have been professionally printed in large quantity.
A quick survey on the WWW shows that number cards are available in a very wide variety of designs and styles. Points to consider before buying such cards are outlined ~