10 by 10 by 10 Investing Plan

In honor of “dimes,” I’m going to outline a little investing plan today called 10 by 10 by 10. I think just about anybody could implement this plan, especially if you follow some of the awesome savings ideas offered here on A Dime Saved.

The Basics of 10 by 10 by 10

If one can save $10 on each of 10 separate purchases in a given month, and then repeat that behavior for 10 months out of the year, then my mathematical prowess suggests that this person would save $1000 a year. @BestInterest_JC Click To TweetOr you can mix up the numbers as you see fit. But 10 by 10 by 10 is catchy, like those TV lawyers and their easy phone numbers.

In the following 10 minutes (hey!), I’m going to break this plan down step by step:

  • First, what are some simple ways that a person could save those $10?
  • And, which of these opportunities for saving are repeatable, or frequent enough to accomplish multiple times in a given year?
  • Then, we’ll cover some ideas about sticking to the saving habit
  • Finally, what do we do with the savings? And what kind of long-term profits can we hope to reap?

10 Ideas for Saving 100 Dimes

10 ideas for saving 100 dimes

Saving $10 is easier said than done. But that said, it’s still pretty easy!

If I can quickly come up with the following 10 ideas in one session, then I know you all could double my list twice as fast!

  • Haircuts–In the past 10 years, I’ve gotten haircuts on the spectrum of $35 down to $15. At most price points, I know it’s possible to find cheaper barbers.
  • Alcohol–Skip the bar. As much as a $3 pint of the local lager sounds like a good deal, it’s only because we’ve been programmed to forget that bars are 5x as expensive as grocery stores. Grab a 12-pack and get together at an apartment instead.
  • Grocery shopping–On average, I spend $280 per month. Is it feasible that I find $10, or 3.6%, savings in there? Seems reasonable!
  • Gifts–Last year, I spent $932 on ~15 various weddings, birthdays, and of course, Christmas. Of course, I really enjoy spending money on gifts that I know other people would enjoy. But could I turn that $932 into an $832, and still make people happy? Yeah!
  • Library–This might be my favorite one on the list. In the past year, I’ve loaned ~20 books from the library. Is this some weird Millennial humble brag? No! It’s 20 instances where I used to spend $15-$20, and no longer do.
  • Car Insurance–“Just one call and you can save 15%!” The thing is, it’s kinda true! If you haven’t shopped around for car insurance in the past two years, or at least called your insurer to ask for a better deal, then I highly recommend you try. I was recently able to drop my monthly payment from ~$70 to ~$55. That’s 150 Dimes each month!
  • Utilities–Personally, my “heavy hitter” was installing a programmable thermostat. It cost ~$40, and I estimate my winter heating bill went down by about 20%. In snowy Rochester, NY, that equated to about $120 in savings last winter.
  • Switch to a High Yield Savings Account (HYSA)–I only learned about Ally Bank a few months ago, but it took me about 15 minutes to pull the trigger and create my account. Overnight, I went from getting about .50 a month in interest from my old local credit union to about $25 a month now.
  • Share subscriptions–Doesn’t it kinda feel like everything is a subscription service? Now, I understand some things aren’t easily shared, but other services (looking at you, Netflix!) are easy to share with a friend.
  • But first, Craigslist” (or Facebook Marketplace, or consignment shops, etc)–When buying consumer goods, do you need it new? Sometimes, the answer is absolutely! But I easily save $10 a month by buying certain items used.


And that’s 10! I didn’t even mention lattes!

One thing you might notice…I’ve pulling some pretty precise information. The cost of my haircuts? The number of birthday gifts I bought? I budget and track everything I spend. But don’t worry, because I’m wayyy on the extreme end of the spectrum (featuring great input from A Dime Saved!) While I highly recommend a budget, there are many different ways to responsibly understand where your money is going.

Sticking to the Dime Saving Habit

It might sound cheesy, but saving money is just as much a mindset as it is an action. One of the keys to this mindset, in my opinion, is the idea temet nosce, or know thyself. If you get to know yourself–and how you react to certain purchasing scenarios–you’ll be better prepared to not spend that money.

I know the kinds of items that I like to buy–I call it my “buy that!” brain. I know that cool gadgets, however infrequently I’ll use them, get me really interested. I know that I’ve dropped many a $20 bill on an interesting book. Over time, I’ve learned to anticipate my “buy that!” brain. And now that I know myself better, I’ve been able to combat my “buy that!” impulses.

And if you’re going to make saving money a habit, you’ll want to find a way to adhere to that habit; adherence is more important than the details of the saving itself. That is, I’d rather see someone succeed at a 5 by 5 by 5 plan that completely fail at a 10 by 10 by 10 plan. My recommendation: give yourself a reminder before making a purchase. Ask yourself, is there a way I can save $10 on this? One way I’ve implemented this reminder is by putting a physical object–a rubber band–around my credit card. When I remove the rubber band, it kinda forces me to think, “Why is this here? Oh yeah…”

As much as we like to think we’re eminently in control, most of us are also intimately familiar with regretting purchases we’ve made. You might not be as “in control” as you think you are. Getting to understand your purchasing proclivities and gently nudging yourself before buying–these are two fantastic ways to start saving $10 at a time.

$1000 a year, and then?

If we fast forward through a year of cheaper haircuts, library books, and rubber-banded credit cards, we hope that we’ve amassed a nice $1000 savings. What happens next? Ideally, we invest!

There are lots of different options, but one of the most basic ideas is low-cost index funds. An index fund invests in a wide swath of the market, and therefore tends to rise and fall with the economy. In this way, an index fund is kind of brainless. It just copies what the market does. In investing, brainless is actually pretty good. Investors often pay high fees for the luxury of an “expert’s” brain. But history has repeatedly shown that the experts almost never perform well enough to justify those high fees. Unless you have a lot of faith in your investing skills, or those of someone you pick, you’re probably better off using a low-cost index fund.

I ran a little simulation using software called MATLAB to show you the potential benefits of investing in index funds. I simulated a person investing $1000 per year (from our 10 by 10 by 10 plan) for 30 years. I used market data–average returns and standard deviation–from A Random Walk Down Wall Street, by Burton Malkiel. It’s a great book, FYI. Using the power of MATLAB, I ran this simulation 100,000 times–this type of big data simulation is called Monte Carlo analysis.

To compare against, I also looked at the idea of stuffing the $1000/year under a mattress. This is not a good method. And I looked at a more reasonable method of investing in a HYSA—the high yield savings account that I mentioned in my list of 10 ways to save.

For you math nerds, here are a few of my assumptions:

  • 0.6% average returns every month
  • 4.5% standard deviation on those monthly returns
  • Simulated the market using a Laplace distribution
  • Assumed a 2% annual return in the HYSA

And the results are…!

  • Final $ using the Mattress method: $30,000
  • …using the HYSA method: $41,006
  • Mean of 100K market simulations: $105,800
  • Median: $86,530
  • Maximum: $1,007,600 (whoa!…but remember it’s #1 of 100000)
  • Minimum: $12,419 (yikes!…but again, this is the worst of 100000)
  • Percent of market sims worse than the Mattress: 2.87%
  • Percent of market sims worse than the HYSA: 9.31%

Graph: Mattress is the low red line, and HYSA is just above it in green.

Picture description: Some of the random data…Mattress is the low red line, and HYSA is just above it in green.

What can we make of all this? If you’re purely objective, then look at the median and mean of the data. On average, that’s about where you’d end up. This data is the result of small savings decisions compounded over 30 years. This is why Einstein preached about compound interest. Our average investor essentially tripled up on the Mattress technique, and more than doubled the HYSA technique.

On the other hand, many of us are risk averse. Multiple experiments in behavioral economics have shown that the pain of losing $100 is significantly greater than the joy of winning $100. In the context of this experiment, it means that if you’re the unlucky investor who ends up worse than the HYSA or the Mattress, then you’re probably kicking yourself really, really hard.

For this type of risk averse investor, a diversity of investments could be the cure. Rather than investing in 100% U.S. domestic stocks—which my simulation did—perhaps you could invest in a mixture of big stocks, little stocks, bonds, international stocks, REITs, etc. Conveniently, many of these “asset classes” have index funds associated with them—that is, low-cost “brainless” funds that are ideal for the average citizen investor. Some really smart folks have done a lot of the work for you, and they call these types of diversified index fund portfolios “Lazy Portfolios.” I’ll let you Google some further research on them if you wish.

Parting Words

Will the 10 by 10 by 10 catch on? That’d be cool! Am I next the next Suze Orman? Or Jim Cramer? I hope not.

But I really, really hope you learned something useful, interesting, or share-worthy today.

There are plenty of mundane opportunities to save a few bucks. It takes some practice, and perhaps a little shift in mindset, but saving money can become a routine. And then if you let your savings grow over time, you could be sitting on a big pile of dimes.

-Jesse, from the Best Interest.


Jesse Cramer is an engineer and an avid reader/writer. He runs the blog The Best Interest, which started as his creative outlet but gained recognition for explaining complex personal finance ideas in simple terms. Jesse discusses money basics, like your net worth targets by age or the most common unknowns in personal finance. He writes about successful behavioral concepts, like the Fulfillment Curve or learning the biggest lesson from the COVID-19 pandemic. Habits matter too. Developing the habit of tracking every expense with YNAB helped boost his savings rate to over 60% in 2019. Many of his posts have been directly influenced by his readers’ feedback. He says it’s the most fun part of writing his blog.

5 thoughts on “10 by 10 by 10 Investing Plan”

  1. Wonderful article–and some quality information here that deserves a re-read. And, I’m so glad you chose not to mention cutting back on avocado toast and Starbucks as ways to save money. Those aren’t the things that keeping normal people like me from saving! It’s a lack of focus on doing math–which you seem to do pretty well.


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