﻿ Practice with Order of Operations
PRACTICE WITH ORDER OF OPERATIONS
• PRACTICE (online exercises and printable worksheets)
Want more details, more exercises? Read the full text!

The order that operations are to be performed (when not clearly identified)
is summarized with the following memory device:

Please   Excuse   My   Dear   Aunt   Sally    (PEMDAS)

• Do things inside Parentheses first (using PEMDAS, if needed, inside the parentheses).
• Then do all Exponents, in order as they occur, going from left to right.
• Then do all Multiplications/Divisions (they have equal weight) in order as they occur, going from left to right.
• Finally, do all Additions/Subtractions (they have equal weight) in order as they occur, going from left to right.

In September 2017, this problem was floating around the web:

Here's the solution, with correct order of operations: \begin{alignat}{2} 1 + 1 + \,&1 +\, 1 + 11 + 1 + 1 + 1 + 11 + 1\times 0 + 1&& \cr &= 1 + 1 + 1 + 1 + 11 + 1 + 1 + 1 + 11 + (1\times 0) + 1 &\qquad&\text{(the multiplication gets done first)} \cr &= 1 + 1 + 1 + 1 + 11 + 1 + 1 + 1 + 11 + 0 + 1\cr &= 30 \end{alignat} If this doesn't make sense to you, try the following mental exercise on a shorter (but similar) problem: $1 + 2 \times 0 + 3$
• Replace each plus sign with an (equally-weak) person.
• Replace the multiplication sign with a strong person.
Why? Multiplication is ‘stronger than’ addition!
And this makes perfectly good sense, since multiplication is ‘super-addition’: for example, $\,5\times 2 = 2 + 2 + 2 + 2 + 2\,$.
• The first (left-most) weak guy is trying to pull together the $\,1\,$ and the $\,2\,$, to add them.
• The middle (strong) guy is trying to pull together the $\,2\,$ and the $\,0\,$, to multiply them.
• The right-most weak guy is trying to pull together the $\,0\,$ and the $\,3\,$, to add them.
• Who wins? Clearly, the strong guy!

1 2 0 3
$$1 + 2 \times 0 + 3 \ \ =\ \ 1 + \overbrace{(2\times 0)}^{\text{strong guy wins}} + 3 \ \ =\ \ 1 + 0 + 3 \ \ =\ \ 4$$
MORE EXAMPLES:
$-1 + 3\times 5 - 2 = -1 + (3\times 5) - 2 = 12$
$2 - 10\div 5 + 3 = 2 - \frac{10}{5} + 3 = 3$
Master the ideas from this section

When you're done practicing, move on to the optional section:
Laurel, Yanny, Cookies, Bananas, and Clocks

Or, move on to:
Taking PEMDAS Too Literally: Don't Make This Mistake!

Feel free to use a pencil and scrap paper to work these problems.
However, do not use your calculator!

Simplify: