What number is the next logical number in the sequence 15 24 25 5 14 15?

take the first three numbers and the remaining three numbers, they both have the same patern: 15+9=24 24+1=25 and 5+9=14 14+1=15

now what relates both groups is the division of the last number of the 1st group by 5 to get the first number of the remaining three which is also 5 (check it)

now repeating the same thing for 15 (the last of the second three) you will get 3 then 3+9=12 then 12+1=13