A '''multiplication algorithm''' is an [[algorithm]] (or method) to [[multiplication|multiply]] two numbers. Depending on the size of the numbers, different algorithms are in use. Efficient multiplication algorithms have existed since the advent of the decimal system.
==Grid methodG==
Both factors are broken up ("partitioned") into their hundreds, tens and units parts, and the products of the parts are then calculated explicitly in a relatively simple multiplication-only stage, before these contributions are then totalled to give the final answer in a separate addition stage.<div style="float:right">▼
{{main|Grid method multiplication}}
The [[grid method multiplication|grid method]] (or box method) is an introductory method for multiple-digit multiplication that is often taught to pupils at [[primary school]] or [[elementary school]] level. It has been a standard part of the national primary-school mathematics curriculum in England and Wales since the late 1990s.<ref>Gary Eason, [http://news.bbc.co.uk/1/hi/education/639937.stm Back to school for parents], ''[[BBC News]]'', 13 February 2000<br>[[Rob Eastaway]], [http://www.bbc.co.uk/news/magazine-11258175 Why parents can't do maths today], ''[[BBC News]]'', 10 September 2010</ref>
▲Both factors are broken up ("partitioned") into their hundreds, tens and units parts, and the products of the parts are then calculated explicitly in a relatively simple multiplication-only stage, before these contributions are then totalled to give the final answer in a separate addition stage.
The calculation 34 × 13, for example, could be computed using the grid:
