Which number(s) below would not in scientific notation and why? 4.5 x 10^4 6 x 10^7 12.5 x 10^3 4.2 x 10^-8 2.355 x 10^6 0.45 x 10^3

Scientific notation has exactly one non-zero digit to the left of the decimal point in the mantissa. The numbers listed above do not.

Comment on these numbers

There may be good reasons for writing the numbers in this form. For example, in engineering, it is often useful to have the exponent be a multiple of 3. In other instances, writing the number in these forms may facilitate arithmetic. However good the reasons may be, these numbers are not in in the form defined as "scientific notation."