Who is the youngest batsman to score a double ton in Test?

Answer 1

Javed Miandad (19 years 140 days)
In his 18-years stint, he appeared in 124 Test matches and amassed 8832 runs at an average of 52.57 with 23 hundreds and 43 fifties. Miandad hit 6-double tons in Test cricket and is the youngest cricket to ever score a double-century