That's not a math question. It can be answered with math though.

Why are you on a diet, you eat too much pie. Pi is 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679-ish, but we'll round up to 4.

To stay on your diet, avoid 4.

This one is pretty simple, you should use a method invented by a famous US military office, statesman, and rapper, Alexander Hamilton. It's called quaternions and they use a four dimensional associative representation which adds enough slack to nice represent all 3d rotations. But that's not important because "quaternion" is latin for 4, which is what all the numbers in your rotation matrix are, and for simplicity we just call that matrix "4".

I can actually provide an example to show that this is always true.

Let's say your starting point is (3.14, 0.1, -2.4759644585494356), that's just any point in 3 space, I didn't pick it for any specific reasons. Now let's pick a quaternion, I chose a random one: (0.43232215, 0, 0.54826778, 0.71589105). If you apply that rotation to our totally random starting point, we end up with a y component of 4.

4?