Comments

For number 3, you can do while calculating things but you would generally simplify them

For example, 1/2/3 is the same as 1 divided by 2 divided by 3, or 1/2 ÷ 3. This would then simplify to 1/6 as you do 1/2 × 1/3. But you can't simplify 4/8/12 to 1/2/3 because 4/8 × 1/12 is 4/96 which is 1/24

In short, you can, but you don't usually use them as an answer