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Ron Harris

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Your Money Is Worth More Now Than Ever

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3 Practical Ways to Put the Rule of 72 to Work

3 Practical Ways to Put the Rule of 72 to Work

The Rule of 72 is useful for all kinds of financial estimates and understanding the nature of compound interest.

Here are a few examples of how the Rule of 72 can be utilized in the real world to get an estimate about how money will compound in various situations.

Example 1 - Estimating the Growth of an Inheritance.
You inherit $100,000 at the age of 29. What interest rate must you earn for it to become $1 million by the time you turn 65? You’ve got 36 years for your money to grow to $1 million, so it will take 3.25 doubles to grow $100,000 to $1 million dollars. Dividing 36 years by 3.25 doubles equals 11. Your money must double every 11 years. Knowing that, now you can run the formula to find your interest rate: 72 ÷ 11 = 6.54.

There you go. You need a financial vehicle that can offer no less than a 6.5% rate of return to hit your goal.

Example 2 - Estimating the Growth of an Economy.
Let’s say you want to approximate the growth rate of your country’s Gross Domestic Product (GDP). If your GDP is growing at 3% a year you can use the Rule of 72 formula: 72 ÷ 3 = 24. Therefore, in approximately 24 years, your nation’s GDP will double. Unless of course it changes. Were it to slip to 2% growth, how many years would the economy take to double? 72 ÷ 2 = 36 years. Should growth increase to 4%, GDP doubles in only 18 years (72 ÷ 4 = 18).

Example 3 - Estimating Inflation, Tuition, & Interest.
If the inflation rate moves from 2% to 3%, the time it will take for your money to lose half its value decreases from 36 to 24 years. If college tuition increase at 5% per year, costs will double in 14.4 years (72 ÷ 5 = 14.4). If you pay 15% interest on your credit cards, the amount you owe will double in only 4.8 years (72 ÷ 15 = 4.8)!

– Tom Mathews & Andy Horner

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The Middle Class Saves…The Rich Invest

October 7, 2020

The Middle Class Saves…The Rich Invest

Saving money is a good habit, but a bad strategy.

That’s why the rich focus on investing. While the masses are getting .09% interest on their passbook savings account,(1) the rich are pursuing returns of 5% or more on the same money. That means with a $10,000 investment paying .09% interest, the saver pockets a whopping $9 per year. That same $10,000 investment paying 5% interest yields a $500 return.

Wealthy people know that a little strategy goes a long way, and when it comes to money, that could make the difference between a comfortable and miserable retirement. The good news is that you don’t have to have a PhD in finance to become a competent investor; you simply have to know how money works. While the masses may be buying used luxury cars, second homes, and living beyond their means, the rich are more inclined to create assets that leverage the power of compound interest and other people’s time—such as retirement accounts that yield interest, part-time businesses, and property. The rich put their money to work, while the masses simply go to work.

The secret to better investing is maximizing returns while managing risk. The rich rarely get greedy, and usually settle for reasonable returns with minimal risk. They generally don’t expose their financial future to the wild swings of the market. They know that the enemy of the investor is losing money, so they lean more towards calculated risks where returns are respectable and losses are not likely. It’s the old professional baseball strategy: Forget about hitting home runs and just get on base. Sure, it’s not as sexy as knocking the ball out of the park or being able to brag to your friends that you made a 50% return, but it reduces your exposure while simultaneously providing you with the potential to become incrementally wealthier every day.

Start by learning the Rule of 72, the Time Value of Money, and the concept of Wealth Equivalency. Next, learn how to protect your family from the fallout of premature death while building cash value you can eventually withdraw tax-advantaged. Lastly, learn how to leverage long-term care insurance for pennies on the dollar by adding it as a low cost rider on a life insurance contract. More people go broke from medical issues than any other reason.(2) These basic strategies will start you on your way to financial success.

Our book, How Money Works: Stop Being a Sucker, will take you through the 7 Money Milestones. Study these milestones and contact your financial professional to put the proper strategies in place. If you take action, you can alleviate any worries about your financial future. It’s that powerful of a process. Once you’ve implemented these strategies, you can focus on the other things that really matter in your life. Give yourself the gift of financial security. You deserve it.

— Steve Siebold

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The Rule of 72 Explained

October 5, 2020

The Rule of 72 Explained

In our book HowMoneyWorks: Stop Being a Sucker, we introduce the Rule of 72, a mental math shortcut for estimating the effect of any growth rate—from quick financial calculations to population estimates.

This formula is especially useful for financial estimates and understanding the nature of compound interest. Rates of return may not be the easiest subject for consumers since it isn’t taught in schools, but this simple rule can help show the significance of a percentage point here or time horizon there.

Here’s the formula: 72 ÷ Interest Rate = Years to Double. If you know the interest rate (or rate of appreciation) or the time in years, dividing 72 by that number will give you a good approximation of the unknown number.

When will your money double?* 72 ÷ 1% = 72 years to double 72 ÷ 3% = 24 years to double 72 ÷ 6% = 12 years to double 72 ÷ 9% = 8 years to double 72 ÷ 12% = 6 years to double

Here’s an example: If you’re receiving a 9% rate of return, just divide 72 by 9. The result is 8. That means your money will double in approximately 8 years. Maybe that’s not fast enough for you and you prefer your money to double every 5 years. Then simply divide 72 by 5. The result is 14.4. Now you know you need a 14.4% return to achieve your goal.

This rule, long known to accountants and bankers, provides a close idea of the time needed for capital to double.

If you think that a difference of 1% or 2% is insignificant—think again! You seriously underestimate the power of compound interest. If one account appreciates at 9% and another at 12%, the Rule of 72 tells you that the first will take 8 years to double while the second will need only six years. This formula is also useful for understanding the nature of compound interest.


  • At 6% interest, your money takes 72 ÷ 6 = 12 years to double.
  • To double your money in 10 years, you need an interest rate of 72 ÷ 10, or 7.2%.
  • If inflation grows at 3% a year, the prices of things will double in 72 ÷ 3, or 24, years. If inflation slips to 2%, it will double in 36 years. If inflation increases to 4%, prices double in 18 years.
  • If college tuition increases at 5% per year (which is faster than inflation), tuition costs will double in 72 ÷ 5, or about 14.4, years.
  • If you pay 17% interest on your credit cards, the amount you owe will double in only 72 ÷ 17, or 4.2, years!

The Rule of 72 shows that a “small” 1% change can make a big difference over time. That small difference could mean buying the house you want, sending your kids to the college they choose, retiring when you wish, leaving your children the legacy they deserve, or settling for… something less. Doing the math with the Rule of 72 can give you critical insight to hit your goals down the road by shifting your strategy accordingly.

By the way, the Rule of 72 applies to any type of percentage, including something like population. Can you see why a population growth rate of 2% vs. 3% could be a huge problem for planning? Instead of needing to double your capacity in 36 years, you only have 24. Twelve years were shaved off your schedule with one percentage point faster growth.

The Rule of 72 was originally discovered by Italian mathematician Bartolomeo de Pacioli (1446-1517). Referring to compound interest, Professor Albert Einstein (1879-1955) is quoted as saying: “It’s the greatest mathematical discovery of all time.” He called it the 8th Wonder of the World—it works for you or against you. Make sure you put this shortcut to work the next time you consider an interest rate. When you save, it works for you. When you borrow, it works against you!

— Tom Mathews

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  • The Rule of 72 is a mathematical concept that approximates the number of years it will take to double the principal at a constant rate of return compounded over time. All figures are for illustrative purposes only, and do not reflect the performance risks, fees, expenses or taxes associated with an actual investment. If these costs were reflected, the amounts shown would be lower and the time to double would be longer. The rate of return of investments fluctuates over time and, as a result, the actual time it will take an investment to double in value cannot be predicted with any certainty. Investing entails risk, including possible loss of principal. Results are rounded for illustrative purposes. Actual results in each case are slightly higher or lower.

Let’s Talk About Money

September 30, 2020

Let’s Talk About Money

Women earn 82 cents for every $1 earned by a man.¹

As women, we take time away from our careers to care for children, parents, and partners. Interruptions like these can significantly impact a woman’s chance for promotion, ability to earn higher income levels, and—for some women—vesting in full retirement benefits.²

The COVID-19 crisis has made it even harder for women. Without childcare, mothers of young children have had to reduce their work hours 4-5 times as much as fathers, widening the gender gap in work hours. It may seem small or even temporary now, but it heralds a big step backward in the progress women have made in gender equality at work. Fathers—on the other hand, who continued to work full hours during the pandemic, will likely benefit from upcoming promotions and raises over the next couple of years.³

Talk About Money
If we want change, we need to start having open conversations about money. We should talk with our friends and co-workers about money over lunch. We should talk to our families and our kids about money at dinner. We have to talk about the things we’re concerned about, and stop keeping silent because we’re embarrassed, guilty, or ashamed. Have you thought about these questions:

  • Can I make more money?
  • How do I stop living paycheck to paycheck?
  • What’s the best way to reduce my debt?
  • Do I have enough money to retire?

As women, we’re comfortable talking about anything and everything with our friends—except for money. It’s that one boundary we rarely cross. The majority of women would rather talk about their own death before they’ll talk about money.⁴ When women start asking questions and talking openly about things that are important to us, the world changes. There is power in our words and intentions.

Save More Money
From a financial perspective, women say their biggest regret is not investing enough money. We hold back because we don’t feel like we know enough.⁵ Banish the doubts and do 2 things. First, start your journey to learn how money works. It’s not as complicated as you may think. Focus on the basics like the power of compound interest, the time value of money, and the Rule of 72.

Second, develop the habit of setting aside money every day or every week. This can be money from your current discretionary income. If you don’t think you have any extra income, then find it by reducing your expenses or create it with an increase in your income. Skip the latte, bag your lunch, or cut out something extra in your day or week. Without taking into account any potential growth from investing, the chart below shows how saving a little bit every day can add up over time.

Savings Amount Per DayTotal In A MonthTotal In A Year

The Next Normal Doesn’t Have to be the Old Normal
We may not see equal pay or equal wealth in 50 or 100 years or more. The traditional workplace is outdated. We can’t expect the Next Normal to be any different from the Old Normal unless we each take steps to bring about change for ourselves. It all starts with bringing our concerns into the light with real questions and open conversations.

— Kim Scouller

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