Let's find out how much 5 * 10^5 is:
10^5 = 100000 (basically include 5 zeroes after the 1)
5 * 100000 = 500000
Now the question is asking how many times larger is that compared to 1 * 10^5?
Well we know 10^5 = 1000000, and 1 * anything is that number. So 1 * 10^5 = 100000.
This means that 5*10^5 is 5 times larger than 1*10^5