The "math" contained within this blog ranges from the purely mathematical equation (e.g., takt time, average) to metrics (e.g., inventory turns, order fill) to pseudomathematical (e.g., change management, waste elimination effectiveness) to concept introduction (e.g., hypothesis tests) to data and math integrity considerations (e.g., gauge repeatability and reproducibility, measurement system validation). So, the reader is bound to run into formulas, symbols, and mathematical definitions.
We try to keep things as simple as possible. Nevertheless, the following table of mathematical symbols may serve as a handy reference.
Category

Symbol

Name

Definition

Example

Basic Math

= 
equals sign

equality

7 = 4+3 
> 
strict inequality

greater than

7>6 
< 
strict inequality

less than

7<8 
≥ 
inequality

greater than or equal to

7≥6 
≤ 
inequality

less than or equal to

7≤8 
( ) 
parentheses

calculate expression inside first

3x(4+1) = 15 
[] 
brackets

calculate expression inside first

[(3+2)x(2+5)]=35 
+ 
plus sign

addition

3+2=5 
 
minus sign

subtraction

52=3 
x 
times sign

multiplication

3x5=15 
/ 
division slash

division

8/2=4 
¯ 
horizontal line

division/fraction


a^{b} 
power

exponent

3^{2}=9 
√ 
square root


√9=±3 
Algebra

{ } 
braces

set



floor brackets

rounds number to lower integer



ceiling brackets

rounds number to upper integer



nearest integer

rounds positive number to nearest integer


x 
single vertical bar

absolute value

3=3 
(a,b) 
open interval



∑ 
sigma

summation – sum of all values in a range or series


Probability and statistics

P(A) 
probability function

probability of event A

P(A)=0.7 
P(A∩B) 
probability of events intersection

probability of events A and B

P(A∩B)=0.7 
P(AUB) 
probability of events union

probability of events A or B

P(AUB)=0.7 
P(AB) 
conditional probability

probability of event A given event B occurred

P(AB)=0.5 

overbar or bar

sample average

