Is it always true that **AB** = **BA**?

**NO!**
Even when both
products can be formed they are rarely equal.

For example, calculate both of the following products (you might wish to use paper and pencil):

Problem | Think First | Result |
---|---|---|

This shows that in general for matrices **A** and **B**, **AB** ≠ **BA**.

Is **A**_{4×4} **0**_{4×4} = **0**_{4×4} **A**_{4×4},
where **0** is the zero matrtix?