Math Problem

[Lingering]

I still don't see why it's done like that. I've never understood how it made sense to start in the middle of a problem rather than from left to right, unless there are parentheses.

 

The reason is so everyone does it the same, otherwise people will word things out differently, the reason for the order is also so you don't end up with negitive numbers unless they are meant to be there,

[79wjd]

Think of it this way. You have to keep like with like. This make sense? And multiplication is just a shorthand way of doing addition. So you have to do the multiplication first in order to get it into a form of addition.

 

[Guest]

21 obvs

[smjpl]

 

The logic works for very simple maths but probably will break down with more complicated problems. I couldn't think of a better way to explain why the ordering is important.

[TheRetiredSlave]

but WHY. Parentheses I get, but multiplying and dividing before adding and subtracting makes no sense to me.

 

Lets say that you have 4 bottles of beer and you add two 6-packs of beer, the solution would be 4 + 2 * 6 = 16 beers total..

 

If you were to add the two to the four before you multiplied it, the result would be 36, which we logically would know is incorrect if you were adding four individual beers to two 6-packs of beer.. 

[Trik'Stari]

Lets say that you have 4 bottles of beer and you add two 6-packs of beer, the solution would be 4 + 2 * 6 = 16 beers total..

 

If you were to add the two to the four before you multiplied it, the result would be 36, which we logically would know is incorrect if you were adding four individual beers to two 6-packs of beer.. 

When you could just do 4+12

[ManWithBeard1990]

but WHY. Parentheses I get, but multiplying and dividing before adding and subtracting makes no sense to me.

It's just the best way to do it. It's the order in which you're least likely to need to write down parentheses when you're writing down a mathematical problem. It's the most common way to express a mathematical problem. You'll understand why later. When you'll need to solve more complex equations you'll be happy the rules are the way they are because it'd be tedious to use parentheses on everything that has higher priority than what's on the left.

 

Mind you, attempts have been made in the past to make it simpler. Polish notation and reverse polish notation, for example, did not follow the same rules and an expression were solved in identical steps independent of what operator is being used. You just needed to write everything down in the correct order it needed to be solved. No parentheses were necessary. It's beautiful, and it was an easy-to-process way to input things into the early scientific calculators of the time, but there's a problem: When a mathematical problem is written out in words it can be hard to see at a glance where all the numbers went  into the mathematical expression. It doesn't lend itself to doing equations either, so you're stuck with the traditional system for that as well.

 

In time, you'll learn to appreciate the math for why it is the way it is. It's logical, but you're going to need to learn more about it to see the beauty of that logic. Don't worry, it'll come.

[Robi_g]

Weird I know this as BODMAS

It was always BIDMAS for me

[ManWithBeard1990]

When you could just do 4+12

Exactly. That's basically why multiplication goes before addition. It just makes sense that way. I just saw on your profile that you're actually older than me so I doubt you'll eventually appreciate it fully. That's okay though.

[TheRetiredSlave]

When you could just do 4+12

 

That was exactly my point. 2 * 6 is 12..