Economics & Personal Finance
Lesson 2 of 2 8 min +45 XP

Budgeting & Compound Interest

Making money grow over time.

What you'll learn

  • Build a simple budget
  • Explain compound interest
  • Contrast saving with borrowing
The snowball that grows itself

Save $100 at interest and next year you earn interest on the interest too — the snowball grows faster the longer it rolls. Compound interest is why starting to save early beats saving more later, and budgeting is what feeds the snowball.

Your money can work for you

A budget is a plan: money in versus money out. Save part of what comes in, and interest can multiply it. Compound interest means you earn interest on your interest, so savings snowball — the earlier you start, the larger the snowball. The same force works against you on debt.

Simulation · Compound interest grower
yr 0yr 4yr 8yr 12yr 16yr 20

$500 grows to $1935 compounded — vs $1200 with simple interest.

Change the deposit, rate, and years to watch compound growth pull ahead of simple interest.

Lab · Two savers
  1. Saver A puts away $500 at 7% and leaves it for 30 years.
  2. Saver B waits 10 years, then saves the same $500 at 7% for 20 years.
  3. Use the simulation to estimate each final amount.
  4. Explain why starting earlier matters more than the amount.

What you should see: You saw compound interest reward time, and why early saving beats late saving.

Knowledge Check

+15 XP / correct

1. Compound interest is powerful because you earn interest on…

2. A budget is basically a plan comparing…