Mr. Tucker's Money Class

Mr. Tucker's Penny Challenge · Chapter 8

I'm hiring you for a one-month job. How do you want to be paid?

Every year I asked every one of my economics classes this question. Hands shot up before I finished the sentence. Pick one before you scroll.

DAY1of 31
The penny pays that day$0.01
Total paid so far$0.01

Pick Option A or Option B to start the clock.

The lesson: slow at first, then huge

On day 20 the penny pays $5,242.88, and the $100,000 crowd feels smart. On day 25 it pays $167,772.16 in a single day. On day 31 it pays $10,737,418.24, and the whole month adds up to about $21.5 million.

Real savings don't double every day. Nothing does. But the shape is the same: slow, then faster, then shockingly fast. Most people quit during the "day 20" part. Start early, be patient, and wait for day 25.

See it with real numbers in the compound interest calculator →

See all 31 days

General education only, not personal financial, tax, or investment advice.

Free calculators from the book

Every tool matches the book's worked examples

Each calculator opens with the example from its chapter, so you can check your answers against the book. Then type in your own numbers. Nothing you type leaves this page.

Scan a QR code in the book, or type the short address from your chapter: tuckersmoneyclass.com/penny, /paycheck, /car-loan and so on.

Part 1 · Earning

Part 2 · Budgeting

Part 3 · Saving and Interest

Part 4 · Credit and Debt

Part 5 · Investing Basics

Part 6 · Protecting What You Build

Part 1 · Earning

Chapter 1 · Your First Paycheck

Paycheck take-home estimator

Where did the money go? Enter your hours and pay, plus the federal and state withholding from your pay stub. Social Security (6.2%) and Medicare (1.45%) are figured for you.

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From your pay stub. It depends on your W-4 and income.
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Some states, like Texas and Florida, have none.

General education only, not personal financial, tax, or investment advice. Other deductions, like health insurance or a 401(k), are not included. Social Security has a yearly wage cap that most young workers will not reach.

Part 2 · Budgeting

Chapter 3 · Building Your First Budget

50/30/20 budget builder

Split your monthly take-home pay: 50% for needs, 30% for wants, 20% for savings and paying down debt. It's a starting guideline, not a law.

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Sinking fund

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General education only, not personal financial, tax, or investment advice. In expensive cities, needs may take more than 50%.

Chapter 4 · Needs, Wants, and Opportunity Cost

Habit cost: the "latte factor"

What does a small daily habit really cost? Compare spending it with investing the same money once a year.

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7% is the book's after-inflation estimate. No guarantees.

General education only, not personal financial, tax, or investment advice. Assumes one deposit at the end of each year, compounded once a year. Real returns go up and down.

Chapter 6 · Your First Apartment and Car

Can I afford to move out?

Don't ask "Can I pay the rent?" Ask "Can I pay for the whole life that comes with it?" Check the 30% rent guideline, then run a full month.

The rent test

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The monthly budget

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Move-in day cash

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General education only, not personal financial, tax, or investment advice. The 30% guideline uses gross (before-tax) pay. Get real quotes for insurance and utilities.

Part 3 · Saving and Interest

Chapters 8–9 · Compound Interest · Time Is Your Superpower

Compound interest and the Rule of 72

Same $100 a month, different starting ages. Watch what time does. Interest is compounded monthly and deposits go in at the end of each month.

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7% is roughly the long-run stock market average after inflation. Some years drop a lot.

Rule of 72

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General education only, not personal financial, tax, or investment advice. An illustration, not a promise. A savings account would pay much less than 7%.

Chapter 10 · The Emergency Fund

Emergency fund planner

The guideline is 3 to 6 months of essential expenses: the bills you must pay to live and work. Start with a $500 to $1,000 starter fund.

Monthly essentials

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Your plan

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General education only, not personal financial, tax, or investment advice. Months are rounded up to whole months.

Part 4 · Credit and Debt

Chapter 11 · How Borrowing Works

Car loan payment and true cost

Don't shop by monthly payment alone. A longer loan lowers the payment and raises the price. See the payment, the total interest, and what the car really costs each month.

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Other monthly car costs

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General education only, not personal financial, tax, or investment advice. Interest is figured monthly. A lender's schedule may differ by a few cents because of rounding.

Chapter 12 · Credit Cards: Tool or Trap?

Credit card payoff: minimum vs. a fixed payment

Assume you stop using the card. Compare paying only the minimum with paying the same amount every month.

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Example minimum rule from the book: the greater of 1% of the balance plus that month's interest, or $25. Your card's rule is in your card agreement.

General education only, not personal financial, tax, or investment advice. Interest is charged once a month here. Real cards usually figure it daily, so real results differ slightly.

Chapter 15 · Student Loans: The Ticking Time Bomb

Student loan "ticking time bomb"

Unsubsidized loans build interest from the day the money is paid out: through school, the six-month grace period, and any forbearance. Follow the fuse from the first loan to the last payment.

Unsubsidized loans, by year

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Interest builds for 4.5, 3.5, 2.5 and 1.5 years before repayment (four years of school plus the grace period).
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Subsidized vs. unsubsidized: one loan

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General education only, not personal financial, tax, or investment advice. Uses simple interest before repayment and assumes unpaid interest is capitalized when repayment starts and after forbearance. When interest capitalizes depends on the loan type and current rules; check StudentAid.gov.

Part 5 · Investing Basics

Chapter 18 · Mutual Funds, Index Funds, and ETFs

Fund fee comparison

Two funds hold the same investments. One charges more each year. The fee comes out of your return every year, and the gap compounds.

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General education only, not personal financial, tax, or investment advice. Compounded once a year, no taxes. Real returns vary from year to year.

Chapter 20 · Retirement Accounts

401(k) match and "$1 million by 65"

How much a month gets you to $1,000,000 by 65? The answer depends hugely on when you start.

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Employer match: free money check

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% of pay
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General education only, not personal financial, tax, or investment advice. Assumes end-of-month deposits at a steady return with no taxes, fees or withdrawals. Check your plan's vesting rules.

Part 6 · Protecting What You Build

Chapter 24 · Your 10-Year Money Plan

Net worth tracker

What you own minus what you owe. Fill it in once a year using what each item is worth today, and watch the number move.

Assets (what you own)

Liabilities (what you owe)

General education only, not personal financial, tax, or investment advice. Nothing you type is saved or sent anywhere. Write your yearly totals in the book's tracker.

Free practice game · Chapter 19 · Any age, no sign-up

Mr. Tucker's Practice Market

Start with $10,000 of play money. Buy and sell made-up companies and index funds using a real order ticket: market, limit and stop orders, bid and ask, and fractional shares. Press Next day or Next week to move time forward and see what happens.

Simulated prices with made-up companies, for education only.

What happened

    Order ticket

    1. Buy or sell
    3. Quantity: shares or dollars
    shares
    Fractional shares are OK, like 0.25 (up to 4 decimal places).

    5. Bid, ask and spread: shown under the ticker.

    7. Extended hours: off. This game trades regular hours only.

    Where are margin, options and short selling? Left out on purpose. They are the fastest ways for a beginner to lose more than they planned. Read why in Chapter 19 of Mr. Tucker's Money Class: "What the Other Buttons Mean (and Why to Leave Them Alone for Now)."

    Prices

    Tap a ticker to put it on your order ticket. You buy at the ask and sell at the bid. The gap between them is the spread.

    Open orders

    Limit and stop orders wait here. Each time you move to the next day, they are checked against that day's prices.

    Your portfolio

    Your total valueIf you'd put it all in the Total Market Index Fund on day 1
    Activity log

      New game

      Your game saves in this browser. Teachers: give the class the same game number and length, and everyone gets the same prices.

      Your next step

      Ready for real prices?

      When the order ticket feels easy, practice with real stocks and funds at real market prices. Still play money, still free.

      Mr. Tucker's pick

      Virtual Stock Exchange by Stock-Trak

      Free. Real-time prices from 40+ exchanges around the world, built-in investing lessons, and tools to join a contest or create one for friends, family or a class.

      Go to virtual-stock-exchange.com

      MarketWatch Virtual Stock Exchange

      Another free option, for players 16 and older.

      marketwatch.com/games
      New contest every quarter · Q1 starts Jan 1, 2027

      Join the Mr. Tucker's Money Class contest

      A free contest on Virtual Stock Exchange with real-time prices. A new contest starts every quarter, so there's always a fresh start. The first one runs January through March 2027. Sign up now and trade against other readers.

      Join the contest

      Setting up your own game? Use the book's settings:

      • Starting cash: $10,000
      • Margin: off. Short selling: off.
      • Limit orders: on
      • Length: at least three months. One week of trading teaches you about luck, not investing.

      Simulated prices with made-up companies, for education only. The companies, tickers, prices and news here are invented and do not match any real company or fund. Not personal financial, tax, or investment advice. No commissions; you pay only the bid/ask spread.

      For the Money Smart kids books

      Sam's three jars

      Give some, save some, spend some, and be patient! Split your money into three jars, then see how long until you reach your savings goal.

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      Spend is whatever is left, so the jars always add up to 100%.

      Savings goal

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      General education only, not personal financial, tax, or investment advice. Grown-ups: this tool pairs with Sam Saves!, Sam's Lemonade Stand and Sam Gets Money Smart.

      Books by Robert B. Tucker

      The books

      Every calculator on this site goes with a book. Story coloring books for little ones, money books for kids, and a real-life money workbook for teens and young adults. Download free sample pages from any coloring book to print and color at home or in class.

      Book list loading…

      For teachers, homeschool groups and parents

      Free printables

      Classroom-ready worksheets that go with the books. These are on the way.

      Coming soon

      Penny Challenge worksheet

      Fill in all 31 days, then answer the questions. Answer key included.

      Coming soon

      Three jars chart

      A give, save and spend tracker for the Money Smart kids books.

      Coming soon

      My first monthly budget

      50/30/20 practice plus a zero-based budget page.

      Coming soon

      Net worth tracker

      A one-page yearly tracker with goals for ages 18, 22 and 25.

      Robert B. Tucker

      About Mr. Tucker

      Robert B. Tucker

      Robert B. Tucker has spent his career where money meets real life. A decorated U.S. Army combat veteran, he went on to work as a financial advisor, helping families plan, save and invest. He brought that experience into the classroom, teaching economics, U.S. history and civics at East Laurens High School in East Dublin, Georgia, where his economics students produced three Georgia InvestWrite state winners in three years, from a small rural school that didn't normally compete in statewide competitions.

      He later owned and ran a manufacturing company, served as chief technology officer of an insurance company, and became CEO of a software company. He has met a payroll, balanced a budget, and invested for the long term.

      U.S. Army combat veteranFormer financial advisorEconomics teacher3 InvestWrite state winnersBusiness owner and CEO

      The books: Mr. Tucker's Money Class: Real-Life Money Lessons from Your First Paycheck to Your First Trade (teens and young adults), and the Money Smart kids series: Sam Saves!, Sam's Lemonade Stand and Sam Gets Money Smart.