1, 49, 162, 5364, ?
[125-135 level]

123456789, 13456789, 1345789, 134578, 13578, ?
Explain.
[145-150 level]

194938764, 5, X, X, 7654, 45678, ?, ?, ?
[150-155 level]

493186758, 824915731, 591848734, 118393749, ?, ?
[160 level]