Base ten blocks, also known as Dienes blocks after popularizer Zoltán Dienes, are a mathematical manipulative used by students to practice counting and elementary arithmetic and develop number sense in the context of the decimal place-value system as a more concrete and direct representation than written Hindu–Arabic numerals. The three-dimensional blocks are made of a solid material such as plastic or wood and generally come in four sizes, each representing a power of ten used as a place in the decimal system: units, longs, flats and blocks. There are also computer programs available that simulate base ten blocks.