The task is to read a passage and convert numbers in their text forms into digit forms. The text numbers can be used to represent Quantity, Dates and Time, Addresses or Positions.

At the time of the assassination the names of about one hundred persons were in this index, all of whom were included in the group of four hundred
At the time of the assassination the names of about 100 persons were in this index, all of whom were included in the group of 400

The Chronicles of Newgate, Volume two. By Arthur Griffiths. Section twelve: Executions, part two.
The Chronicles of Newgate, Volume 2. By Arthur Griffiths. Section 12: Executions, part two.

and the return address was Post Office Box two nine one five, Dallas, Texas.
and the return address was Post Office Box 2915, Dallas, Texas.