Learn how decoder-based Large Language Models work through an innovative spreadsheet-based approach that makes complex AI concepts accessible without requiring coding expertise. Explore GPT-2's complete architecture including tokenization, embeddings, attention mechanisms, and multi-layer perceptrons using a fully functional implementation built entirely in Excel. Discover how spreadsheets can demystify abstract AI concepts by providing a tangible, visual representation of how transformer models process information, making the inner workings of LLMs understandable for engineers from non-ML backgrounds. Gain practical insights into the fundamental building blocks of modern AI systems through this unique educational methodology that eliminates technical barriers while maintaining conceptual depth.