What are four different ways to write "q times r" in symbols?
qr, q × r, q · r, (q)(r)
There may be other correct answers. However, you don't need to go all over-achiever on us. These four are sufficient.
What's wrong with abbreviating "y times 5" as y5?
When multiplying a variable by a number, we write the number first. We could write 5y to mean "y times 5." We could also write y · 5, (y)(5), or y × 5, but these expressions are all longer than 5y. In this instance, shorter is better.