since the odd numbers are in increasing order, and so can only be ordered in one way, they can be generalised to sticks
so you must now sort 4 sticks and 4 numbers, 2, 4, 6, and 8
eg |2|4|6|8 = 1 2 3 4 5 6 7 8
so how many ways can you arrange the sticks? I believe it is 8C4 = 70 (8 items...