ex=only even digit formations 0,2,4,6,8,

no repetition of digits ie digits without repeating

4,6,8.0=yes

4,6,8.8 = no because it repeats a digit

the formations must be distributed in 7 positions

the difficulty will be how to use 7 positions for 5 even digits using 4 digit formation without repeats ,

attention, the formations without repeating digits must transit (occupy the ones below the 7 positions) not simply make 0,2,4,6,8 by 4, the formations must occupy the 7 positions, that is, keep 3 blank spaces.

we know that 7 positions in 4 different digits have 35 chisels, for example the 8th digit has circular in the 4 options ie it is not crescent.