Question

which number is not written n scientfc notaton? a)15.5 x 10^4 b)2.567x 10^-5 c)6.7 x 10^3 d) none of these

I think D

Answer 1

I think not, a) is written to two digits before the decimal, sci notation has one digit.

Answer 2

Letter A) is not in scientific notation do to the fact that 51. what ever is higher than ten, and to be a valid notation the first number has to be between one and ten, no lower then one and no higher than ten, so letter A) would not be in scientific notation