The Math Trick Billionaires Use to Double Their Money

Sounds too good to be true, right? But here's the thing: doubling your money through investing isn't a scam or get-rich-quick scheme. It's basic math that's been working for decades.

The Rule of 72 is a simple formula that shows exactly when your money will double. No guessing, no hoping, just pure calculation. Financial advisors use it in their heads to estimate investment growth, and by the end of this email, you'll be doing it too.

No finance degree required. Just one formula that takes a few minutes to understand.

The Formula Is Stupidly Simple

Here it is:

72 ÷ Annual Return Rate = Years to Double Your Money

But wait—what's a "return rate"? Let's break it down a little bit further if you’re having trouble understanding “return rate.”

What Does "Return Rate" Actually Mean?

A return rate (also called rate of return) is just how much your investment grows each year. This is typically shown as a percentage.

Think of it like this: if you put $100 into an investment and one year later it's worth $108, you earned $8. $8 is 8% of your $100 investment = an 8% return.

So when someone says an investment "earns 8% per year," they mean: for every $100 you put in, you make $8 in profit annually.

Now let's use that in the Rule of 72.

How to Actually Use This

Now, let’s run the formula. Let’s say you invest $1,000 in something with an 8% annual return.

Using the Rule of 72: 72 ÷ 8 = 9 years

(Remember: that means your $1,000 grows by $80 in year one, but thanks to compound interest, it grows even faster in the following years).

Your $1,000 becomes $2,000 in roughly 9 years, without you doing anything except waiting.

At 6% annual returns? 72 ÷ 6 = 12 years to double.

At 10%? 7.2 years.

See how it works?

The formula works because of compound interest: you earn returns not just on your original investment, but also on the returns you've already earned. Your money grows exponentially, not linearly, which is why time is your biggest advantage.

A Real-World Example: The Vanguard S&P 500 ETF

Disclaimer: This is not an endorsement of any specific product or investment advice. Always do your own research or consider consulting with me directly if you need more advice by visiting my website, SergioAvedian.com.

This is a perfect example of how the Rule of 72 plays out in real life.

The Vanguard S&P 500 S&P 500 ETF (ticker: VOO) tracks the 500 largest companies in America. Over the past 30 years, it's delivered a 10.49% compound annual return.

This isn't a lucky streak. It's been consistently profitable across multiple market crashes, recessions, and economic crises, including the 2008 financial crisis and the 2020 pandemic crash.

Let's apply the Rule of 72:

• 10.49% annual return → 72 ÷ 10.49 = 6.9 years to double

Here's what that looks like if you invested $10,000 today:

• Year 7: $20,000

• Year 14: $40,000

• Year 21: $80,000

• Year 28: $160,000

And this isn't hypothetical. From September 2010 to November 2025, a $10,000 investment in VOO actually turned into $80,690, a 706.90% total return with dividends reinvested. VOO actually outperformed its standard 10% return!

Why This Type of Investment Works

Index funds, like the Vanguard S&P 500, are considered safe and reliable because you're not betting on one company, you're investing in 500 of them at once. If one company tanks, the other 499 cushion the blow.

The S&P 500 has averaged around 10% annual returns since 1957, even when you factor in every major crash and recession. It's not about timing the market perfectly, it's about time IN the market.

Even Warren Buffett, one of the most successful investors of all time, banks on this strategy. His 90/10 rule? Put 90% in an S&P 500 index fund (something like VOO also works), 10% in bonds, and let time do the work.

The Bottom Line

The Rule of 72 isn't just a math trick—it's a mindset shift.

You don't need to chase meme stocks or find the next big thing. You just need to start early, stay consistent, and let compound interest do the heavy lifting.

Your move: Take 5 minutes today to calculate how long it'll take to double whatever you're working with right now. Then ask yourself: "Can I start this earlier than I planned?"

Because the earlier you start, the more doublings you get. And more doublings = exponentially more wealth.

That's the magic ✨