A coefficient is a multiplicative factor in some term of a polynomial, a series, or any expression. Note that all the examples for coefficients precede variables in wikipedia.org/wiki/Coefficient,. They are sometimes depicted in non-italicized boldfaced letters defined as constants for given equations, but they always precede variables. Note that no example is listed for use without the subsequent variable, even in the case of a series.
The only official exception to this is in physics, where it’s used as a constant for conversion in an equation, where it usually precedes a variable.
The example in shmoop.com (which sounds like a pet name for a lover) though understandable, is, in fact, arbitrary. The unshmoopified, formal and official name for this portion of the expression is mantissa. So, technically, that IS NOT the nomenclature or definitions used for the parts of a number in scientific notation:
Yes, shmoopy, it’s easy to understand that portion could be called a coefficient. I think it’s a great alternative name. However, this post is a pedantic, hair-splitting, mathematical definition, which does not allow for casual vocabulary.
...Though there is always some room for sweet-talk.
