Solve the problem.
-Mark can remember only the first 5 digits of his friend's phone number. He also knows that the number has 7 digits and that the last digit is not a 0. If Mark were to dial all of the possible numbers
And if it takes him 25 seconds to try each one, how long would it take to try every possibility?

Question

Quizplus · Accepted Answer

There are 10 possibilities for each of the first 5 digits, and 9 possibilities for the last digit. So, there are 10 * 10 * 10 * 10 * 10 * 9 = 900,000 possibilities. At 25 seconds per try, it would take 900,000 * 25 seconds = 22,500,000 seconds to try every possibility. This is equal to 37.5 minutes.

Solve the Problem. -Mark Can Remember Only the First 5 Digits of His