This is a school term, sometimes used in teaching math. The word has no formal mathematical definition. A model for base 10 numeration. Ten copies of […]

Any counting number, other than 1, can be built by adding two or more smaller counting numbers. But only some counting numbers can be composed by multiplying two or more smaller counting numbers.

Number tricks are fun for children. The fun, all by itself, is valuable, but is not mathematics. But understanding how the trick works is good mathematical, often algebraic, learning.