Mastering Fast Calculations with Fingers

Aug 3, 2024

Kung Fu Mathematics Lecture Notes

Introduction

  • Overview of videos showcasing fast finger calculation methods.
  • Objective: Learn to solve long addition and subtraction using fingers as an abacus.
  • Title: "Kung Fu Mathematics"

Sponsorship

  • Introduction of Speedwrite: A tool to help students with assignment deadlines by rewriting text in a unique way using AI.

What is Kung Fu Mathematics?

  • Kung Fu Mathematics: Method involves using fingers to perform rapid calculations.
  • Origin: Known as Cheese and Bob (Chisholm Bob).
  • Source: The Complete Book of Chisholm Bob by Young Pi.

Brain Functionality in Math

  • Brain primarily counts; less memory usage compared to traditional methods.
  • Traditional methods require tracking answers, causing mental stress.

Representing Numbers on Hands

Representation of 1 to 99

  • Right Hand: Represents numbers 1-9.
    • 1: one finger up, 2: two fingers up, ..., 5: all five fingers up, ..., 9: all fingers up.
  • Left Hand: Represents tens.
    • 10, 20, 30, 40, 50, 60, 70, 80, 90.

Examples of Number Representation

  1. Represent 12: 10 (left hand) + 2 (right hand) = 12.
  2. Represent 28: 20 (left hand) + 8 (right hand) = 28.
  3. Represent 36: 30 (left hand) + 6 (right hand) = 36.

Addition with Fingers

Example Problem: 73 + 25

  1. Represent 73: 70 (left) + 3 (right) = 73.
  2. Represent 25: 20 (left) + 5 (right) = 25.
  3. Combine: Result is 98 (90 + 8 = 98).

Overcoming Limitations

  • Limited to 10 fingers; must be creative with calculations.
  • Example Problem: 32 + 28.
    • Represent 32: 30 (left) + 2 (right).
    • For 28, add 50 and subtract 30 instead.

Subtraction with Fingers

Example Problem: 54 - 32

  1. Represent 54: 50 (left) + 4 (right).
  2. Subtract 30 first: subtract 50, then add 20.
  3. Final count gives 22.

Long Addition Example

Problem: 15 + 12 + 8 + 29...

  1. Represent each number sequentially.
  2. Use finger rules to add without tracking total mentally.
  3. Final total: 94.

Extending to Hundreds

Representation of 100-999

  • Use half open fingers to represent hundreds:
    • 100: all fingers closed.
    • 200: half open, etc.

Practice Problem: 68 + 49

  1. Represent 68: 60 (left) + 8 (right).
  2. Add 40 (add 100, subtract 60).
  3. Add 9 using techniques discussed.
  4. Final total: 117.

Conclusion

  • Practice is crucial for mastering Kung Fu Mathematics.
  • Challenge yourself to solve higher numbers (e.g., 482 + 394).
  • Opportunity for additional practice with the Math Blob Run game.
  • Join the community on Discord for more math resources.
  • Final Note: "Math is everything!"