The Hamburg Set comprises fifteen cards depicting the five basic mathematical symbols and the single digits 0 through 9. The Hamburg Set is part of the Elbe Set of Mathematical Learning Cards ~ which is described elsewhere [elbe]. There are several subsets of cards ~ named after cities and towns on the river Elbe.
For convenience of pricing for postage four packs of the Hamburg Set are packed and bundled into a postage-paid package called the Wittenberg Set [wittenberg].
A slightly different bundle ~ the Cuxhaven Set [cuxhaven]~ includes two sets of numerals and just one set of symbols.