Learn how mathematicians write ideas as expressions — including exponents, variables, and equivalent forms.
Quick read-throughs in plain language — then hit the videos below.
4³ means 4 × 4 × 4 = 64. PEMDAS tells you the order: Parentheses, Exponents, Multiply/Divide, Add/Subtract.
In 3 + 4 × 2, multiply first: 3 + 8 = 11. Parentheses come first: (3 + 4) × 2 = 14.
Try it
What is 2 + 3² × 2?
By the end of this unit, you should be able to:
Each video covers one topic from this unit — read the short blurb below to find the right one.
Plug in values and simplify expressions that include powers.
Watch on YouTubePEMDAS step by step so you always know what to do first.
Watch on YouTubeTurn word phrases like "five more than x" into algebra.
Watch on YouTubeWhy letters stand for unknown numbers in math.
Watch on YouTubeLearn terms, coefficients, and constants in an expression.
Watch on YouTubeTell the difference between these three types of math statements.
Watch on YouTubeDifferent-looking expressions that have the same value.
Watch on YouTubeAdd or subtract terms that share the same variable part.
Watch on YouTubeA second take on distributing, with extra examples.
Watch on YouTubeHand-picked links from Khan Academy and trusted worksheet libraries.
A few quick questions to make sure the big ideas stuck. Retake as many times as you want.
Unit 3: Expressions & Equations
Evaluate: 2 + 3 × (4² − 6)
