This is a complete browser-based recreation of the Texas Instruments BA II Plus financial calculator — the industry-standard tool used by CFA, CPA, and finance professionals worldwide.

No installs. No build step. No frameworks. Pure HTML + CSS + JS.

Try it live → parthkhannax.github.io/ba2plus-calculator

• Authentic dark charcoal body with olive-green LCD display
• Yellow 2ND labels on every key matching the real device
• Smooth key-press animations and active states
• Responsive layout — scales from 320px mobile to widescreen desktop
• Zero-jank on iOS Safari, Android Chrome, and all desktop browsers

┌─────────────────────────────────────────────┐
│  ░░░░░░░░░░░ LCD (olive green) ░░░░░░░░░░░  │
│              0,3200                          │
├──────────────────────────────────────────────┤
│  [CPT]  [ENTER]  [↑]  [↓]  [=]             │
│  [2ND]  [CF]    [NPV] [IRR] [→]            │
│  [N]    [I/Y]   [PV]  [PMT] [FV]           │
│  [%]    [√x]    [x²]  [1/x] [÷]            │
│  [INV]  [(]     [)]   [yˣ]  [×]            │
│  [LN]   [7]     [8]   [9]   [−]            │
│  [STO]  [4]     [5]   [6]   [+]            │
│  [RCL]  [1]     [2]   [3]   [=]            │
│  [CE|C] [0]     [.]   [+/−]               │
└─────────────────────────────────────────────┘

Single-column layout fills the phone screen with finger-sized tap targets.

git clone https://github.com/parthkhannax/ba2plus-calculator.git
cd ba2plus-calculator
open index.html        # macOS
# or just double-click index.html in any file manager

# 1. Fork this repo on GitHub, then:
git clone https://github.com/YOUR_USERNAME/ba2plus-calculator.git
cd ba2plus-calculator

# 2. In your repo: Settings → Pages → Source = GitHub Actions
# 3. Push any change to trigger deployment:
git commit --allow-empty -m "Deploy"
git push origin main

# Your site will be live at:
# https://YOUR_USERNAME.github.io/ba2plus-calculator/

1. Press any TVM key (N, I/Y, PV, PMT, FV) — the worksheet opens
2. Fill in the 4 known values
3. Press the CPT [variable] button for the unknown
4. Result appears on the display and fills the field

Example — Loan payment:

N   = 360    (30-year mortgage = 360 monthly payments)
I/Y = 6      (6% annual rate)
PV  = 300000 (loan amount)
FV  = 0

→ CPT PMT = -1,798.65

1. Press CF — the cash flow worksheet opens
2. Enter CF0 (initial outflow, usually negative)
3. Press + Add CF Period for each subsequent period
4. Set frequency (×) for repeated cash flows
5. Enter I/Y % discount rate, then press CPT NPV
6. Or press CPT IRR to solve for the rate where NPV = 0

Example — Project evaluation:

CF0 = -10000
CF1 = 3000 (× 1)
CF2 = 4000 (× 1)
CF3 = 5000 (× 1)
I/Y = 10%

→ NPV = 823.02
→ IRR = 14.35%

1. Press STO — a register grid (0–9) appears showing current stored values
2. Tap a register number to store the current display value
3. Press RCL and tap a register to recall it to the display

The 2ND key activates the gold secondary functions shown above each key:

• 2ND + CPT → QUIT (resets display to 0, closes all panels)
• 2ND + LN → eˣ (e raised to current value)
• 2ND + = → ANS (recall last result)

ba2plus-calculator/
├── index.html          # Calculator markup (semantic HTML5)
├── styles.css          # Full layout + responsive design (500 lines)
├── script.js           # Calculator engine + TVM/CF/NPV/IRR logic (600 lines)
├── .github/
│   └── workflows/
│       └── deploy.yml  # GitHub Pages auto-deploy workflow
└── README.md

No build tools. No package.json. No node_modules.
The entire calculator is three files you can read start-to-finish in an afternoon.

Uses closed-form solutions for FV, PV, and PMT. Solves N and I/Y via bisection root-finding on the standard TVM equation:

PV·(1+r)ⁿ + PMT·[(1+r)ⁿ − 1]/r + FV = 0

Standard discounted cash flow with support for frequency-grouped cash flows:

NPV = CF0 + Σ [ CFt / (1+r)^t ]

Solved via bisection on NPV(r) = 0 with bracket expansion for convergence across any sign pattern.

Pull requests are welcome. For major changes, open an issue first.

1. Fork the repo
2. Create a branch: git checkout -b feature/your-feature
3. Commit your changes: git commit -m 'Add: your feature'
4. Push and open a PR

Ideas for contributions:

• Amortization schedule worksheet
• Bond pricing worksheet
• Depreciation worksheet (SL, SOYD, DB)
• Dark/light theme toggle
• History log panel

MIT — free to use, modify, and distribute.