What is the scientific notation of 0.00277?

What is the value of x in the this question ?

What is 1/3x5 on anuber line what does it look like on a number line

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236