Instructional programs from
prekindergarten through grade 12 should enable all students to
 understand numbers, ways of representing numbers, relationships among
numbers, and number systems;
 understand meanings of operations and how they relate to one another;
 compute fluently and make reasonable
estimates.

Number pervades all areas of mathematics. The
other four Content Standards as well as all five Process Standards are grounded
in number.
Central to the Number and Operations Standard is
the development of number sense. Students with number sense naturally decompose
numbers, use particular numbers as referents, solve problems using the
relationships among operations and knowledge about the baseten system, estimate
a reasonable result for a problem, and have a disposition to make sense of
numbers, problems, and results. For example, children in the lower elementary
grades can learn that numbers can be decomposed and thought about in many
different waysthat 24 is 2 tens and 4 ones and also two sets of 12.
Computational fluencyhaving and using efficient
and accurate methods for computingis essential. Students should be able to
perform computations in different ways, including
mental calculations, estimation, and paperandpencil calculations using
mathematically sound algorithms. All students should use calculators at
appropriate times, setting the calculator aside when the instructional focus is
on developing computational algorithms. Computational fluency should develop in
tandem with understanding.