[Math] Right to left and order of operations

arithmetic

Reposting since I am unable to validate the previous account,I asked the same question

https://math.stackexchange.com/questions/674426/right-to-left-order

Can someone please clarify unable to understand this basic math 🙁

I am sorry if this too basic math to ask

How can i represent this statement without order of precedence/ with order of precedence in a right to left flow

3+5/2*7-6

What I think : when we use right to left with no order the statement would come as

(7-6) = 1
(2*1) = 2
(5/2) = 2.5
3+2.5 = 5.5
when we use right to left with order the statement would come as

2*7 = 14
5/14 = 0.35
3+0.35 =3.35
3.35-6 = -3.35
Am I right about the above statements? How will right to left affect the order of operations?

Please clarify

Best Answer

What you call it is right to left, but don't you really mean left to right? The operations may be right justified in the calculator, but no expression is ever evaluated right to left. Where did you hear about this? Maybe you can explain this to me, but I'm afraid I don't think I know what you're talking about. mathematical expressions are evaluated in the order in which they are written, not reverse order. Am I missing something?

The correct way to evaluate $3+5/2\cdot7-6$ (with multiplicative precedence) is $$\begin{align}3+(\tfrac{5}{2}\cdot7)-6&=3+(2.5\cdot7)-6\\&=3+17.5-6\\&=14.5\end{align}$$ Simple left-to-right order would be $$\begin{align}(3+5)/2\cdot7-6&=8/2\cdot7-6\\&=4\cdot7-6\\&=28-6\\&=22\end{align}$$ Right-to-left order is complete nonsense.