Dan found a two digit odd number one of its digits was half the other the number was greater than 50 what number did Dan find?

If the last number is 1 - > 21 <50

if the last number is 3 - > 63 > 50 OK

if the last number is 5 - > 105 which is not a two digits number

if the first number is 4 - > 42<50

if the first number is 6 - > we get 63 again

if the first number is 8 - > we get 83 which is not odd

63 is the only answer