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Abacus that Makes Use of the Decimal System
Last updated at November 24, 2025 by Teachoo
Abacus that Makes Use of the Decimal System
Class 8 (Ganita Prakash & Old NCERT)
Chapter 3 Class 8 - A Story of Numbers (Ganita Prakash)
- Introduction
- The Mechanism of Counting
- Some Early Number Systems
- Roman Numerals
- Figure it out - Page 60, 61
- Egyptian Number System
- Variations on the Egyptian System and the Notion of Base
- Adding Egyptian Numerals
- Multiplying Egyptian Numerals
- Distributive Law – For Egyptian Numerals
-
Abacus that Makes Use of the Decimal System
- Shortcomings of the Egyptian System
- Figure it out - Page 69
- Mesopotamian Number System
- Mayan Number System
- Chinese Number System
- Hindu Number System
- Evolution of Ideas in Number Representation
- Figure it out - Page 80
Transcript
Abacus that Makes Use of the Decimal SystemAbacus was a device was used around the 11th century to help people calculate using the "Place Value" system, even if they were still writing with Roman Numerals! How the Abacus Board Works The board is like a grid. The most important part is the Horizontal Lines. Each line represents a specific "Place Value" (power of 10), just like our modern math. Bottom Line: Represents 1s (Units) Second Line: Represents 10s (Tens) Third Line: Represents 100s (Hundreds) Top Line: Represents 1000s (Thousands) How to Read the "Counters" (Beads) This system has a special rule for where you place the beads (counters) to save space. Bead ON the line: Value = 1 (times the place value). Bead ABOVE the line: Value = 5 (times the place value). Let's verify this We use the example number in the text: 3426 1000s Line: 3 beads on the line = 3000. 100s Line: 4 beads on the line = 400. 10s Line: 2 beads on the line = 20. 1s Line: 1 bead above (which means 5) + 1 bead on the line (1). Total 5 + 1 = 6. Total: 3000 + 400 + 20 + 6 = 3,426
