4. In order to conver the number 0.00045 from standard form to scientific notation, consider that te scientific notation is of the form:
m x 10ⁿ
where m is a number between 1 and 10 and n is an integer number.
Moreover, take into account that n is negative if the number on standard form has zeros left side the first non-zero number. The value of n, depends of the number of places you have to move the decimal point to obtain a value m greater than 1 and lower than 10. You can notice you have to move the decimal point 4 places, then n = -4, and m = 4.5.
Hence:
0.00045 = 4.5 x 10⁻⁴
5. Consider, the exponent -3 as four zeros left side of 1.27, just as follow:
1.27 x 10⁻³ = 0.00127