Guides

Short, plain-English explanations of the math behind the calculators, with worked examples you can check.

Order of operations (PEMDAS)
The order of operations in plain English: parentheses, exponents, multiply and divide left to right, add and subtract left to right. Worked examples and the common traps.
Degrees and radians
What degrees and radians are, how to convert between them (multiply by π/180 or 180/π), a table of common angles, and why your calculator gives the wrong sine in the wrong mode.
How to graph a function
How to graph a function by hand and with a graphing calculator: make a table of values, find the intercepts, plot and join the points. Worked examples for a line and a parabola.
How loan payments are calculated
The loan payment formula in plain English, a worked example for a $200,000 mortgage at 6% for 30 years ($1,199.10 a month), and why most of the early payments go to interest.
Binary, decimal and hexadecimal
How binary (base 2), decimal (base 10) and hexadecimal (base 16) work, how to convert between them by hand, a 0–15 table, and what two's complement means for negative numbers.