Complete practical guide
The spreadsheet template book about thirty-one formulas that were wrong
37 chapters and 68 printable worksheets on selling spreadsheet templates - why a broken one gives you a number instead of an error, why the customer will never tell you, and why sixty-eight calculations outsold two hundred and sixty-six.
Look inside — read the first chapter freeOne payment, USD. Yours permanently — no subscription.
What this guide is
Rae built a bookkeeping workbook for small service businesses: 214 formulas, 31 validation rules, 12 named ranges, 9 conditional formats - 266 calculations, about seventy hours. It sold steadily and the reviews were kind. In month six a customer wrote to say the quarterly totals column had been wrong 'for a while.' Their dates had been typed in a different order and pasted from a bank export; some were read as different valid dates, some became text. The formula did not complain. It added up the rows it recognised, ignored the ones it did not, and printed a total that was smaller than the truth by an amount neither of them could see. Rae spent two days with a calculator and a sheet of paper, working out by hand what each calculation should return before looking at what it did return. Thirty-one of the 266 were wrong or misleading under at least one of five ordinary inputs - a blank cell, a currency symbol typed in, a date in the other order, a negative, or a second application. Three of the four dashboard figures were among them. Before that week, the number of formulas Rae had ever compared against an independently worked answer was zero. The rebuild had sixty-eight calculations, took about twenty-six hours, sold better at a similar price, and generated about a third of the support. That is this business: your product fails by producing a confidently formatted number, the customer trusts it completely, and they will assume any oddity was their own mistake.
What you get out of it
Specifics, not promises.
- The hand-check - an answer worked out on paper before the formula runs
- The five inputs that produce a wrong number and no warning
- Why a date typed the other way round is the most destructive input in this trade
- The fifteen-item publishing gate that a tired evening cannot argue with
- Why sixty-eight calculations outsold two hundred and sixty-six at the same price
- How to test in an application you have never opened, and what to do first
- The six questions that diagnose a fault without ever seeing the customer's data
- The correction notice almost nobody sends, and why it is remembered
- Why five of seven revenue layers require no new calculations at all
- 148 AI prompts - and not one of them writes a formula, deliberately
Ideal for
People designing or selling spreadsheet templates - budgeting workbooks, expense and mileage trackers, planners, inventory sheets, project schedules, invoicing tools and small-business dashboards - and particularly three groups. Somebody who has never compared one of their own formulas against an answer worked out on paper. Somebody selling a workbook on its feature or sheet count. And anybody whose listing currently says it works with any spreadsheet application.
- Anybody designing or selling budgeting, tracking, planning, inventory, project or business spreadsheets
- Somebody who has never compared one of their formulas against an answer worked out on paper
- Somebody selling a workbook on its sheet or feature count
- Anybody whose listing says it works with any spreadsheet application
What's inside
Format
- Digital download, delivered instantly after payment
- Formatted for letter paper — read on screen or print it
- Yours permanently, re-downloadable from your library any time
- Licensed for use in your own business
By the end you can
A reader finishes with a customer defined as a decision rather than a topic; a written purpose sentence that rejects every calculation not serving it; a calculation ceiling set from how long a hand-check actually takes them; one flat entry table with views reading from it, categories held in an editable list rather than typed inside formulas, ranges that extend, and nothing hidden doing essential work; a test case of eight to twelve rows small enough to compute on paper and deliberately awkward; a formula record holding, for every calculation, a plain-words description, a test input, an expected answer worked out independently BEFORE the formula ran, the result, and the date and application version it last passed in; a full hand-check run against five hostile inputs - an empty cell, text where a number belongs, a date in the other order, a negative value, and a second application - in every environment claimed; a publishing gate of fifteen yes-or-no items that no tired evening can talk its way past; an environment statement in the first three lines of the listing naming only what was actually opened, plus the sentence stating that a downloaded copy never receives corrections; a setup sheet inside the workbook carrying purpose, version, licence, support policy, expected date format and the three lines about where to type; a spare untouched copy in every download; licence tiers including a practitioner tier for bookkeepers; a correction notice they would actually send; and stop conditions written as numbers, including the one almost nobody writes - stop publishing, keep the catalogue.
A complete working system for designing and selling spreadsheet templates - built on four rules covering the fact that a spreadsheet's failure mode is a confidently formatted wrong number rather than a visible error, the fact that the product invites the customer to edit the machinery that makes it work, the fact that it must run in applications, versions, devices and locales the seller has never opened where a date order can silently change the answer, and the fact that the data determining whether it works is somebody's private financial records that the seller can never see - with revenue per verified formula as the economic unit, hand-check coverage as the leading indicator, and the hand-check itself as the instrument the trade cannot be run honestly without.
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