[EmxATW5m]

Then you weren't taught the Algebra Order of Operations, and if you weren't taught left-to-right you're in some serious trouble if you don't use it by common sense, even worse if you were taught multiplication over division.

Why? Let's use really simple example
4 / 5 * 6 / 3 * 5

Multiplication first?
4 / 5 * 6 / 3 * 5
= 4 / 30 / 3 * 5
= 4 / 30 / 15
= 0.1333333333333333 / 15
= 0.0088888888888889

Multiplication first, right to left?
4 / 5 * 6 / 3 * 5
= 4 / 5 * 6 / 3 / 15
= 4 / 30 / 3 / 15
= 4 / 30 / 0.2
= 3 / 150
= 0.02

Just right to left?
4 / 5 * 6 / 3 * 5
= 4 / 5 * 6 / 15
= 4 / 5 * 0.4
= 4 / 2
= 2


Correct way, left to right, multiplication and division are equal
4 / 5 * 6 / 3 * 5
= 0.8 * 6 / 3 * 5
= 4.8 / 3 * 5
= 1.6 * 5
= 8

You can ask anyone, 8 is the correct answer, multiplication first, or right to left, or both together both throw you far off from the correct answer.

edit:

Only reason I can figure out it's not taught (in western countries at least) is the fact that we normally read from left to right, too, so teachers might assume that it just comes out naturally.