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Ex 3.1, 4
Last updated at May 7, 2026 by Teachoo
Class 9
Chapter 3 Class 9 - The World of Numbers (Ganita Manjari I)
- The Human Need to Count
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Exercise Set 3.1
- The Revolution of Śhūnya
- Integers
- Exercise Set 3.2
Transcript
Ex 3.1, 4 Ancient Indians used the joints of their fingers to count, a practice still seen today. Each finger has 3 joints, and the thumb is used to count them. How many can you count on one hand? How does this relate to the ancient base-12 counting systems? Thus, we can count till 12 in one hand Now, are asked How does this relate to the ancient base-12 counting systems? This is because humans could easily count to 12 on a single hand without putting down a tool they were holding. Hence, 12 became a very natural "grouping" number. This is why many ancient cultures used base-12 (dozenal) systems, which is the exact reason we still have 12 months in a year, 12 hours on a clock face, and 12 inches in a foot!
