What is the conceptual meaning of scientific notation?

Answer 1

Scientific notation is a way of representing numbers, usually very large or very small, in the form a*10^b where 1 <= |a| < 10 is a decimal number and b is an integer (negative or positive). a is called the mantissa and b is called the exponent.

Answer 2

The concept is that any number can be expressed as a mantissa and a power of ten and that excessive accuracy is often spurious and usually of little real value.