The Oz “Friends Expenses” Demo (and Why Everyone Missed the Point)
Excel education is broken — but it’s nobody’s fault.
This is Part 2 of the series, where we stop talking about theory and watch the break happen in real time.
1. The Original Challenge (Oz’s Video)
One of my favourite Excel explainer videos of all time is Oz du Soleil’s Christmas Expenses example (December 2019).
Three siblings. Shared expenses.
Who owes what to whom?
Oz uses this example to introduce Power Query’s Unpivot feature, and then combines it with SUMIFS to reach the answer.
It’s elegant, well explained, and enormously influential.
A week later, Oz followed up with a second video inspired by Miguel Escobar, showing how the same problem can be solved entirely in Power Query using a self-join.
Both solutions work.
Both teach valuable techniques.
Both are technically correct.
And both quietly plant a very dangerous idea.
2. The Hidden Assumption
The hidden assumption is this:
“This problem is about finding the right Excel technique.”
Unpivot.
Self-joins.
Formulas.
That framing already puts us inside the purple square.
So I reframed the challenge.
3. The Reframe (Where Everything Breaks)
I said:
- It’s not 3 people — it’s the entire cast of Friends
- They’re on a trip to London
- Then add everyone at Central Perk
- Claims come in from anywhere in the world
- Nobody “runs” the spreadsheet
- Full transparency is mandatory
- Claims must be verifiable
- The system must run forever, unattended
At that point, the room always reacts the same way:
“Impossible.”
“You can’t do that in Excel.”
“That needs an app.”
Hands go down.
Confidence collapses.
4. The One-Row Insight Everyone Missed
So I rewind.
I point to a single row:
Bo owes £20
Tanya owes £20
Jay paid
That row is incomplete.
Because if Jay paid £40, Jay is owed £40.
So the correct row is:
Bo +20
Tanya +20
Jay -40
Now the row balances to zero.
Do that for every transaction.
Summarise.
Job done.
No Unpivot.
No Power Query.
No formulas gymnastics.
When I ask the audience which solution they would choose in real life — unanimous.
“That one. Obviously.”
Then comes the punchline:
“If it’s obvious…
why did nobody see it for six years?”
5. The Black Swan Moment
This is a textbook Black Swan pattern:
- Everyone thinks it’s impossible
- Someone does it — and it’s simple
- Everyone says: “Oh, we could have done that”
Four-minute mile.
Everest.
Flight.
And now: Excel.
6. The Live Demo (Where Minds Actually Break)
I then show the scaled version.
- A spreadsheet anywhere in the world
- “Submit Expense” section
- One click: PUT
- One click: GET balances
- One click: drill into transactions
- One click: drill into item splits
Joey questions a charge.
Click — full transparency.
Ross submits a new claim.
Click — balances update globally.
Six people.
Six thousand people.
Same system.
No spreadsheets sent.
No spreadsheets received.
No spreadsheets harmed.
7. “So… What’s the Magic?”
The audience always assumes:
- VBA
- Power Query
- Python
- Something “advanced”
Then I show the file size.
~30KB.
And I explain the three missing ideas.
8. The Three Things Nobody Is Teaching
1. Central Data
Claims don’t belong in spreadsheets.
They belong in a table, centrally located, trusted.
That’s not an Excel problem.
That’s a thinking problem.
2. PUT (Upload)
Excel can write rows directly into a database table.
Click.
Row appended.
Done.
Nobody teaches this.
3. GET (Query)
Excel can query that table directly:
- Summaries
- Breakdowns
- Filters
- Drill-downs
Without Power Query.
Nobody teaches this either.
9. Why Education Is Broken (and Why It’s Nobody’s Fault)
Oz teaches Unpivot — brilliantly.
Miguel teaches self-joins — brilliantly.
What’s broken is not what people teach.
What’s broken is what nobody teaches:
- What a relational database is
- That Excel can create one
- That Excel can write to it
- That Excel can query it
- That this is how Excel scales
Social media teaches the bottom of the pyramid.
Management lives at the top.
Those two worlds never meet.
10. Spray Gun vs Purple Square (Again)
This demo is the spray gun.
- Global
- Simple
- Few moving parts
- End-to-end
- Enterprise-grade
And it’s been hiding inside Excel for decades.
11. Why This Series Exists
Excel education is broken — but it’s nobody’s fault.
People are teaching techniques.
Nobody is teaching architecture.
This series exists to show:
- What you were never shown
- Why it matters
- And why, if you know this,
you should be paid a lot more
Coming Next
Part 3:
Memes, myths, and how social media accidentally trained an entire generation to think small.
If you want, next we can:
- Turn this into a live demo outline
- Cut it into a 15-minute keynote
- Extract a LinkedIn carousel
- Or script it as a Mission: Impossible episode
Just tell me where you want it to land.⬇️ Download as Audio
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