There will probably be times when you want to stop Mathematica in the middle of a calculation. Perhaps you realize that you asked Mathematica to do the wrong thing. Or ...

Cells as Mathematica Expressions Notebooks as Mathematica Expressions Manipulating Notebooks from the Kernel

Different kinds of vector and matrix multiplication. This multiplies each element of the vector by the scalar k. The "dot" operator gives the scalar product of two vectors.

Arithmetic Numerical Mathematics in Mathematica The Uncertainties of Numerical Mathematics

Introduction Finding Expressions That Match a Pattern Naming Pieces of Patterns

Introduction Random Generation Functions Seeding and Localization

Invisible characters. In the input there is an invisible comma between the 1 and 2. Here there is an invisible space between the x and y, interpreted as multiplication.

Introduction General String Patterns Regular Expressions

DataSources[] returns a list of information about named data sources made available through DatabaseResourcesPath.DataSources[name] returns a list of information about the ...

SQLArgument[arg1, arg2, ...] holds a sequence of arguments to an SQL query.