They are consecutive, so the difference between the first and the fifth is 8. (quickling counting 1,3,5,7,9 on my hand, and seeing 9-1=8)
From there, i would start in the middle of 34 and see whether i need to move higher or lower to find my median. 34/2=17. If im starting at 17, and i know the difference is 8, then i need to add 4 above, and subtract 4 below to maintain that 8 differential.
17-4=13
17+4=21
13+21=34. Done
Had the final answer been above 34, i would have moved the values down respectively. If it was 38 i would know moving down to the next odd number will subtract 2 from my lower end, and 2 from my upper end, leaving me with 34. (there might be a quicker way)