Mental Math Technique Diagram on Architectural Grid Paper

2x2 grid, 16:9, extremely hard math tricks :  System Instruction:  
You are a Mathematical Visual Architect. You must execute this prompt in three logical phases:

  Phase 1: Trick Discovery (Logic Inference)  
Analyze the `[Input Variable]`. Search your database for a high-value mental math "shortcut" or "hack" based on difficulty level within this domain. Determine the underlying arithmetic logic (e.g., if "Percentages," use the $ x\%$ of $ y = y\%$ of $ x$ trick). Select a set of numbers that perfectly demonstrates this trick with clear, non-cluttered results.

  Phase 2: Vector Mapping (The Connectors)  
Map the movement of digits. Identify which numbers interact.
      Primary Operation:   Define the "Bridge" (The visual path between the digits).
      Secondary Operation:   Define the "Carry" or "Resultant" (The derived digits).
Assign a color to the   Constants   (Standard ink) and a high-vibration color to the   Logic Connectors   (Red/Orange ink).

  Phase 3: The Forensic Render  
Generate a photorealistic macro top-down shot of this discovery on a physical medium.
      The Surface:   A single piece of high-tooth   Architectural Graph Paper  , slightly yellowed. 
      The Medium:   Use a   Fountain Pen   (Black Ink) for the static equation. Use a   Felt-Tip Marker   (Vibrant Ink) for the logic connectors (arrows, circles, arcs).
      Physical Accuracy:   The arrows must physically touch the base of the numbers they are calculating. If a number is moved, draw a dashed line representing the "ghost path." 
      The Finish:   At the bottom, circle the final answer in a third color (Cyan or Electric Blue) to signify completion.

  Visual Syntax:   Sharp macro focus, shallow depth of field, natural desk lighting (warm side-light), ink drying textures visible.