Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
10BII Calc HD is a business calculator featuring over 100 built-in functions for business, finance, mathematics and statistics
$8.99 · In-app purchases
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Combine features and design from your favorite apps.
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Generating… usually about a minute.
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for 10BII Calc HD: map the core Finance workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Assumption to check: Limited calculation features compared to full financial software
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: No integration with bank accounts for real-time data
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: No customizable user preferences
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Static user interface without any animations
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
10BII Calc HD is a business calculator featuring over 100 built-in functions for business, finance, mathematics and statistics. Easily calculate loan payments, interest rates, amortization, discounted cash-flow analyses, TVM (loans, savings, and leasing), bonds and depreciation using a simplified algebraic entry system. The keyboard and display have been carefully optimized for the iPhone, iPod Touch and iPad. Two keyboard layouts and multiple specialized worksheets allow you to do much more than a 10BII calculator while maintaining compatibility with the standard. HD version includes: • 2 for the price of 1! iPad and iPhone versions included- use on both your iPad and iPhone • HD graphics included for iPad and iPhone retina displays • iPad version includes full support for slide over and split views. • New worksheets including interactive graphs. Features: •Time Value of Money- Loans, savings, leases and amortization schedules using both the standard keyboard and a specialized TVM solver window that displays the contents of all the variables for rapid "what if" solutions to your problems. View and mail amortization tables. •Interest Conversion- Nominal and effective rates. •Cash Flows- Net present value, internal rate of return, net future value and net uniform series calculations. Up to 80 cash flows are easily edited and reviewed using the dedicated cash flow editor screen. Entries are added, deleted and modified in a scrolling display with a touch interface unique to the iPhone. •Business Percentages- Percent change, markup, and margin calculations. •Statistics- Mean, standard deviation, correlation coefficient, and linear regression forecasting, weighted mean. Sample editor and plotter, forecasting using linear, log, exp or power fit. •Conversions- 47 world currency rates and over 100 commonly used metric, english and other conversion factors used in financial, business, scientific and engineering calculations. •Scientific- sin, cos, tan, asin, acos, atan plus the hyperbolic trig functions, conversion between rectangular and polar coordinates, conversion between degrees and radians, time functions including h.ms+ and h.ms-, log, ln, 10^x, e^x, y^x, x root of y, fraction part and integer part. Trig functions can be computed in radians, degrees or gradians. •Worksheets- Auto Purchase Black-Scholes Bond BreakEven Cash Flow Analysis Currency Date Depreciation Interest Conversion Lease Loan Amortization Margin & Markup Refinance Statistics Tip TVM Many of the worksheets include interactive graphs. •Audit tape records all calculations. Tape can be mailed, texted or printed. Discover how to use any function on the keyboard by touching the ? key then the key you want to learn about. Help screens are available for all worksheets. Quote from a customer: "Last week I had a meeting with my accountants and my bankers. We were working on the pro forma balance sheets and cash flows for a new project I'm working on. They were all asking why I had switched to the iPhone for I used to be a die hard "brandX phone" fan. I said that one could do so much more. They said "yea...sure" (they were all using "brandX phones") until I started using your calculator. We were analyzing different payment and amortization schedules. They were so impressed by how easily we could figure out the amount of interest, principal and remaining loan balance for any certain period or combination of periods that in the end they were saying "I have to get me one of those". Great product. Thanks."
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Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.