Numbers that move money.
34 instant calculators for loans, business, websites and AI — plus the Number Lab, which decodes any number's maths, symbolism and memorability. Free, private, no sign-up.
678 · 58 — a rising run (6→7→8) followed by “58”, read in Chinese number culture as “I prosper”. Our mission in five digits: help every visitor's numbers climb.
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Four categories, one goal: faster, better money decisions.
Money & Loans
Loans, mortgages, interest, savings and debt — the decisions that cost or earn you the most.
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Business & Pricing
Margins, break-even, ROI, unit economics and runway for founders and small businesses.
8 tools →
Websites, Creators & AI
Ad revenue, site valuation, domain flips, AI costs and creator earnings.
9 tools →
Everyday Numbers
Percentages, discounts, tips, taxes and price comparisons — fast answers.
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Most-used calculators
Instant results, shareable links, formulas and worked examples on every page.
Compound Interest Calculator
Grow a lump sum plus monthly contributions with any compounding frequency.
Mortgage Calculator
Full monthly housing cost: principal & interest, property tax, insurance and HOA.
Loan EMI Calculator
Monthly payment, total interest and yearly breakdown for any fixed-rate loan.
Break-Even Calculator
Units and revenue needed to cover fixed costs.
Profit Margin Calculator
Gross profit, margin and markup from cost and selling price.
AI API Token Cost Calculator
Monthly cost of an AI feature from requests, tokens and per-million pricing.
Ad Revenue (RPM) Calculator
Estimate display-ad earnings from pageviews and page RPM, with growth.
Percentage Calculator
X% of Y, what percent A is of B, and the reverse.
What does your number say?
Enter a phone number, price, plate or domain. Get its prime factors, binary and Roman forms, digit symbolism, numerology reduction and a 1–99 memorability score.
67858 at a glance
- Prime factors
- 2 × 7 × 37 × 131
- Digit sum
- 34 → reduces to 7
- Binary
- 10000100100010010
- Hex
- 10912
- In words
- sixty-seven thousand eight hundred fifty-eight
- Pattern
- Starts with the viral “67”; contains 678 and 58
Guides worth your time
Plain-English explainers with real numbers you can check.
What Does “6-7” Mean? How a Number Became a Word of the Year
The origin, spread and business lessons of the viral 6-7 meme that Dictionary.com named its 2025 Word of the Year.
6 min read
Numbers & CultureLucky Numbers in Business: Why 8 Sells and 4 Is Avoided
How cultural number symbolism shapes prices, phone numbers, addresses and domains — with practical rules for global businesses.
7 min read
MoneyCompound Interest Explained: The Math That Builds (or Destroys) Wealth
A plain-English guide to compound interest with worked numbers, the Rule of 72, and how it works against you on debt.
7 min read
BusinessBreak-Even Analysis: Know Your Survival Number Before You Launch
How to calculate break-even units and revenue, read contribution margin, and use the result to set prices.
6 min read
BusinessMargin vs Markup: The Pricing Mistake That Quietly Kills Profit
Why a 50% markup is only a 33% margin, with conversion tables and pricing rules.
5 min read
Websites & AIHow Much Can a Website Earn? Traffic, RPM and Valuation Math
The equations behind content-site revenue: pageviews, RPM, affiliate funnels, lead value — and how sites are valued at sale.
7 min read
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Watch & learn
Hand-picked lessons on money, economics and AI from leading educators.
Compound interest introduction
By Khan Academy · via YouTube
What Is Compound Interest?
By Investopedia · via YouTube
How The Economic Machine Works
By Principles by Ray Dalio · via YouTube