I was just wondering, if a series of numbers has 8 digits and the 1st digit is always 3, how many possible combinations of this number could there be. I am certain I once learned this in a math class years ago, but cannot remember how to calculate it. Help would be greatly appreciated. thanks

Question

since the first digit dosn't change, you have 10 possable choices for each of the 7 variable positions, ergo, 10^7 if I understood the question.