Though the Rubix Cube 4x4 may seem an impossible task, especially for those who have a hard time solving the 3x3 version, the work can be partitioned in order to make it easier. Despite breaking the puzzle into manageable chunks, solving the Rubix Cube 4x4 is still difficult, but if it were easy, it wouldn't be as entertaining as it is.
Things You'll Need
 Rubix Cube 4x4

Twist and turn the 4x4 Rubix Cube until you have solved each of the four center squares of each face. Solving each of the four center squares on each face means that you have four squares of the same color at the center of each of the cube's six faces (a different color on each face).

Twist and turn the 4x4 Rubix Cube until you have solved the two outercenter squares on two opposite edges of each face. The four center squares and the outercenter squares must also match to each other.

Solve the Rubix Cube 4x4 as if it were a rubix cube 3x3. Once you've solved the center squares, and two of the outer edges of each face, the 4x4 cube is exactly like a 3x3 cube and can be solved as such. Make sure not to unsolve any of the previously solved squares.
References
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