MAT-144 · Mathematical Reasoning Video Library

ORBITAL Mini Lessons

Every video, cross-referenced with every lesson.

Short evergreen explanations — about three minutes each — that sit alongside the mini lessons and pack the same math tighter. Filter by topic or by pack, or search across every title. Missing videos are on the way; the catalog shape shows what’s coming.

143 available now · 31 uploading soon · 174 videos total in the library

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Every video, cross-referenced with every lesson.

What, Exactly, Is a Function?

Slope Is Just "How Fast"

Where Two Lines Meet

What, Exactly, Is a Function?

The Two Ways Humans Reason

Close Enough Is a Superpower

Slope Is Just "How Fast"

One Equation. Predict the Future.

A Spreadsheet Is a Grid of Functions

Percent Just Means "Out of 100"

One Number, Three Disguises

Tip, Tax, Discount: One Move

Multiply by 1, Convert Anything

60 mph Is How Many Feet per Second?

Tell Your Money Where to Go

What Is Interest? It's Rent on Money

Simple Interest Explained: I = Prt in One Multiply

Compound Interest Explained: Interest That Earns Interest

APR vs APY Explained: The Rate You Actually Earn

What Is an Annuity? Many Payments, One Formula

Future Value of an Annuity: $200 a Month Becomes $244,000

What Is Amortization? Where Loan Payments Actually Go

How to Calculate a Loan Payment (Monthly Payment Formula)

How Car Loans Work: Monthly Payment and Total Interest

Credit Card Minimum Payments: Why You Stay in Debt

Subsidized vs Unsubsidized Student Loans: The Difference

How Mortgage Payments Work: Interest vs Principal

Descriptive vs Inferential Statistics: The Difference

Mean, Median, Mode: Which Average Should You Use?

What Is Standard Deviation? (Explained Simply)

How to Read Histograms, Box Plots, and Bar Charts

The 68-95-99.7 Rule (Normal Distribution Explained)

What Does Margin of Error Mean in a Poll?

What Is Probability? (Favorable Over Total)

The Fundamental Counting Principle Explained

The Addition Rule in Probability: P(A or B) Explained

Permutations vs Combinations: The Swap Test

Expected Value Explained (The Long-Run Average)

Theoretical vs Experimental Probability (Law of Large Numbers)

How to Read Your Paycheck: Gross Pay vs Net Pay

How Tax Brackets Actually Work (Marginal vs Effective Rate)

Tax Refunds Explained: Withholding vs What You Owe

How Stocks Make Money: Capital Gains and Dividends

How Bonds Work: Face Value, Coupon Rate, and Yield

Diversification Explained: The Stock-Bond Split

What Is the y-Intercept, Really?

y = mx + b Is a Machine

The Point-Slope Formula, Explained

Parallel and Perpendicular, in One Picture

Two Points Define a Line

f(x) Is Not f Times x

Domain and Range, in Plain English

The Vertical Line Test, Explained

Find f(3) With No Formula

Where Two Lines Meet

Slope Zero vs Slope Undefined

Negative Slope Isn't Bad

Ax + By = C, Decoded

Percent vs Percentage Points (4% to 6% Is Up 50%)

Stacking Discounts: Why 50% Off Twice Isn't Free

Percent Change Trap: Up 50% Then Down 50% Is a Loss

How to Find the Original Price Before Tax or Discount

How to Add Measurements With Different Units

How to Convert Square Units: Square Yards to Square Feet

How to Convert Fahrenheit to Celsius (and Why It's Weird)

Cross Multiplication Explained: Why It Actually Works

30 Is 20% of What Number? (Find the Whole)

How Exchange Rates Work: Convert Dollars to Euros

Real Rate of Return Explained: Interest vs Inflation

How to Calculate Percent Change (Inflation Example)

The Rule of 72 Explained: How Long to Double Your Money

Compound Interest: Continuous Compounding Explained

Compound Interest: Finding Interest Earned Between Two Years

Present Value Explained: What Future Money Is Worth Today

Compound Interest: Saving at 25 vs 35 Compared

Sinking Funds Explained: How Much to Save per Month

How Much House Can You Afford? (The 28/36 Rule)

Rent vs Buy: The Real Monthly Cost of Owning a Home

What Is PMI? Private Mortgage Insurance Explained