What is the number of tally marks in 9999999?

To represent the number 9,999,999 in tally marks, you would use groups of five tallies. Each group of five is represented as four vertical lines with a fifth diagonal line crossing them. Therefore, 9,999,999 would be shown as 1,999,999 groups of five tallies, plus four additional tallies for the remainder, resulting in a total of 39,999,996 tally marks.