A study desk in warm window light: an open laptop showing the OmniTaught Money Math course, a mug of coffee, an open notebook with a fountain pen, and reading glasses
A hand holding a phone running the OmniTaught app, at a sunlit table with a mug of coffee and a notebook
OmniTaught 🔥 6Topics

Course

Money Math

7 of 13 lessons complete

✓ Loans and APR Intuition
Total cost thinking beats monthly payment thinking · 5 min 100%
9 Inflation Basics
Why the same dollars buy a little less each year · 5 min
10 Spotting Bad Deals
The math tricks stores hope you skip · 6 min
11 Comparing Two Job Offers
Hourly against salary, and everything the number leaves out · 8 min

Lesson 8

Tips and Splitting Bills

All tip math grows from one move: 10% is the decimal shift. Slide the decimal one place left. On a $48 check, 10% is $4.80. Everything else is built from that piece.

20%: double the 10%. $45 check: 10% is $4.50, so 20% is $9. 15%: 10% plus half of it. $60 check: $6 + $3 = $9. 18%: 20% minus a little, or 10% + 5% + a nudge. Close is fine; tips are not landing a plane.

Splitting cleanly: Add the tip before dividing, so nobody has to do a second round. $120 dinner + 20% tip = $144, split 6 ways = $24 each. Round to friendly numbers and let the extra quarters go; friendships outvalue exact change.

Quiz now, while it is fresh. 8 questions, no timer.

1 of 8

What is the fastest mental route to a 20% tip?

The question on the screen is a real one

Do the money math in your head
and actually remember it.

13 lessons, 134 practice questions, 79 flashcards, and 1 timed exam set. Other Math Courses.

Other Math Courses

Built the same way, and every one of them is included.

×%Mental Math EssentialsTimes tables, tips, and percentages: the tricks school skipped 1/2Fractions & DecimalsThe bridge most of us missed, finally explained %Statistics LiteracyRead studies, polls, and headlines without being fooled

And if the thing you need is not on the shelf at all, the Topic Genie builds a full course on anything you name, with the same lessons, questions and review schedule as this one. Beta testers get a code the day they join.

Who builds this

Built by a teacher who became a National Certified Counselor.

OmniTaught is developed by Michael C. Shedrick, M.S., PLPC, NCC: a teacher with a master's degree in educational leadership who went on to become a National Certified Counselor. Both jobs kept exposing the same problem: learning tools that stop at definitions. So this course teaches the working version of its subject, the part you actually use when the real thing is in front of you, and it teaches it the way memory works: a short lesson, a quiz while it is still fresh, and review that brings it back before you lose it.

Also from the same desk, in case they are useful: OmniPsyche Counseling Tools, which preps your next session and not just your notes; OmniPsyche.org, free mental health education with no paywall and no signup; and NOTICE, a free guided meditation app.

What this course covers

Every lesson is short enough to finish in one sitting and ends with questions that make you use what you just read. The last ones are timed, in exam conditions.

  1. Reading Your PaycheckGross, net, and where the missing money went5 min
  2. The 50/30/20 BudgetOne simple split for your take-home pay4 min
  3. Unit PricesThe shelf tag trick that beats the packaging4 min
  4. Sales and Stacked DiscountsWhat 20% off plus 10% off actually comes to5 min
  5. Simple vs Compound InterestThe Rule of 72 and why time is the whole game6 min
  6. Credit Cards and MinimumsWhat a statement is really telling you5 min
Show all 14 lessonsShow fewer
  1. Loans and APR IntuitionTotal cost thinking beats monthly payment thinking5 min
  2. Tips and Splitting BillsRestaurant math in your head, before the check gets cold4 min
  3. Inflation BasicsWhy the same dollars buy a little less each year5 min
  4. Spotting Bad DealsThe math tricks stores hope you skip6 min
  5. Comparing Two Job OffersHourly against salary, and everything the number leaves out8 min
  6. Interest Working For YouThe same math as debt, pointed the other direction8 min
  7. Splitting Costs FairlyThe arithmetic that decides whether people stay friends7 min
  8. Money Math Timed Simulation: Set A30 items, 30 minutes, exam mode30 min

A whole lesson, start to finish

Not a sample and not a summary. This is all of lesson 2, exactly as it reads in the app, and then one of the 3 questions that follow it.

Lesson 2 of 14 · about 4 min

The 50/30/20 Budget

One simple split for your take-home pay

A budget is not a punishment, it is a plan for money you already have. The 50/30/20 rule is a starter split of your net (take-home) pay: 50% to needs, 30% to wants, 20% to savings and extra debt payments.

What goes where

Needs are things with real consequences if unpaid: rent, groceries, utilities, insurance, minimum debt payments, transportation to work. Wants are everything that makes life fun: dining out, streaming, hobbies, upgrades. Savings covers emergency fund, retirement, and paying debt down faster than the minimum.

Do the split in your head

Half of take-home is needs. For the other two: 30% is three times 10%, and 20% is two times 10%. On $3,000 net: 10% is $300, so wants get $900 and savings gets $600.

If your needs eat more than 50%, that is information, not failure. High rent areas do that to people. The rule flexes: maybe you run 60/25/15 for a season. The win is knowing your numbers, not hitting someone else's ratio.

The one move that matters

Automate the 20% on payday. Money that moves to savings before you see it never has to survive willpower.

The 50/30/20 rule is applied to which number?

Where this comes from

OmniTaught is an independent study app and does not represent any government agency. The paycheck figures in these lessons are the published federal rates, and the IRS page below is where the current ones live.

Official sources: IRS, Social Security and Medicare withholding rates

Questions people ask

Is there an app for practicing everyday money math?

Yes. OmniTaught opens in any browser and installs to a phone or a computer like an app, and it works offline once you have opened it. Money Math is 13 lessons, 134 practice questions and 79 flashcards, and the first week is free with no card.

What does Money Math cover?

Paychecks, interest, deals, and tips without a calculator. It is 13 lessons long, plus 1 timed exam set in exam conditions, and every lesson ends with questions on what you just read.

How long is each lesson?

About 6 minutes. There are 13 of them, so the reading comes to under 2 hours in total, and it is built to be done a lesson at a time rather than in one sitting.

How much practice is in it?

134 practice questions, every one with an explanation of why the right answer is right, plus 79 flashcards that come back on a schedule built from how well you knew them last time.

What does it cost?

Nothing for the first week, and no card is asked for. After that OmniTaught is $9.99 a month or $79 a year, which opens every course on the site, this one included, plus one Genie course a month.

Free for a week. Then $9.99 a month.

No card to start.

EVERYTHING INCLUDED
$9.99a month, or $79 a year
  • Every course in the ever-growing library, every quiz, & your review deck.
  • One Genie course a month, built on whatever you name. Extra courses are $6.99 each. Add narration to any Genie made course for $9.99.
  • A free week first, no card needed. Cancel any time from Settings.
Start Money Math free

Flashcard apps have the science but no content. Content sites have no retention engineering. This one has both, built one craft at a time.