Question

How many 5-digit numbers are there with at least one odd digit in them? (mind that the leading digit cannot be 0.)

Answer 1

Answer:

96,875

Step-by-step explanation:

If we allow trailing 0s, then there are 100,000 5-digit numbers.

50,000 have an odd number as the first digit.

Half the the numbers with an even number as the first digit (25,000) have an odd number as the second digit. You can see the pattern that will play out:

50,000 + 25,000 + 12,500 + 6,250 + 3,125 = 96,875

Answer 2

Please see the attachment