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Re: Are we all doing our math correctly?
From: Chris Post
Date: 2017 Jul 10, 21:25 -0700

Lu is essentially correct:

Two equations and solutions, since they both appear in this thread:

"6 divided by 2(2+3)"

= 6/2(2+3)
= 6/2*(2+3)
= 6/2*5
= 3*5
= 15

"6 divided by 2(1+2)"

= 6/2(1+2)
= 6/2*(1+2)
= 6/2*3
= 3*3
= 9

PEMDAS is an acronym for the rules governing which operations are performed first in an equation.

P - Perform operations within PARENTHESES first.

E - Perform operations involving EXPONENTS next.

M/D - Perform operations involving MULTIPLICATION or DIVISION next moving from left to right within the equation.  Multiplication and division are considered to have the same precedence.

A/S - Perform operations involving ADDITION or SUBTRACTION last moving from left to right in the equation.  Addition and subtraction are considered to have the same precedence.

Applying these rules to the first equation: 6/2(2+3):

First op = (2+3) = 5
That yields 6/2*5.
Second op = 6/2 = 3
That yields 3*5 = 15.

The same logic applies to the second equation.

See, e.g., http://www.purplemath.com/modules/orderops.htm Browse Files

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