Working
The calculator measures from the earlier date of birth to the later one: full calendar years first, then full months, then the remaining days.
8 Jan 1935 → 8 Jan 1945 = 10 years
8 Jan 1945 → 8 May 1945 = 4 months
8 May 1945 → 24 May 1945 = 16 days
Age gap = 10 years, 4 months and 16 days = 3,789 total days.