Induction: Building a Practical Calculator

This week I worked on building a Margin Calculator app, starting with a simple idea and gradually turning it into something more useful and practical. The aim of the app is to help users calculate how much profit they are making on a product or sale, while also showing their profit margin, markup and other key figures. I wanted it to solve a real problem: giving people a quick way to understand where they are gaining or losing money without having to work it all out manually.

I began by planning the basic user flow. The first version was kept simple: the user lands on the calculator page, fills in a form with their product details, clicks calculate, and then sees a results page with their figures. The main focus at this stage was functionality rather than design. I made sure the app included the core fields needed for the calculation, such as cost price, selling price, quantity and extra costs. I also planned the key formulas, including total revenue, total cost, profit, profit margin and markup.

Once the basic structure was clear, I improved the app by making the prompt more detailed. This helped the AI understand that the calculator needed more than just a form and a button. I added features such as a currency selector, advanced options for costs like shipping, platform fees, VAT, packaging and marketing, plus a target margin input. I also improved the layout by asking for a clean two-column desktop design, a stacked mobile layout, white cards and a simple blue colour palette. This made the app feel more like a proper tool rather than just a basic calculator.

The biggest improvement this week was adding a smart feature called Smart Loss Analysis. This only appears when the calculation shows the user is losing money. Instead of just showing a negative profit figure, the app explains why the loss is happening and gives practical suggestions based on the numbers entered. It highlights the biggest cost drivers, such as product cost, marketing, shipping, platform fees or discounts, then recommends realistic ways to reduce the loss or move towards break-even. I liked this feature because it made the app feel more helpful and less like a standard calculator.

I also updated the calculations so they were more accurate, especially around discounts. Since a discount reduces revenue, the break-even selling price and target margin selling price needed to account for that properly. This made me think more carefully about how important the logic behind the app is. Even if the design looks clean, the app only works well if the calculations are reliable and the results actually make sense.

Overall, this week helped me understand how to build up an app in stages. I started with a simple working version, then improved the structure, layout, validation and calculations before adding a smarter feature on top. I also learned again that better prompts lead to better results. The more specific I was about the app's purpose, layout, features, edge cases and tone of voice, the more useful the AI output became. Next, I would focus on testing the calculator with lots of different examples to make sure the results stay accurate in every situation, especially when users enter unusual numbers or leave optional fields blank.