why not 7
Consider each cut as separate on each separate shape
first cut makes the cube into two separate cuboids, total cuts =1
next step we do 2 cuts cuts on two separate cuboids ,total cuts=3
next step we got 4 cuboids of same shapes, we do 4 cuts on each cuboid which makes total 8 identical cubes,total cuts =3+4=7
whenever we a cut on cube it will get separated, if its not get seperated at end of 3 cuts too we will get 8 identical cubes