1 / 11

The Abacus

The Abacus. What is it?. The History. Abacus is a Latin word meaning “sand tray” Pebbles replaced the sand Salamis tablet used as early as 300 B.C. by Babylonians Updated by Greeks - using marble & Romans – using bronze Abax –table or tablet Romans added add’l grooves

danika
Télécharger la présentation

The Abacus

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Abacus What is it?

  2. The History • Abacus is a Latin word meaning “sand tray” • Pebbles replaced the sand • Salamis tablet used as early as 300 B.C. by Babylonians • Updated by Greeks - using marble & Romans – using bronze • Abax –table or tablet • Romans added add’l grooves • Corresponded with Roman numerals

  3. The History • Portable devices created • Created by Romans • Could fit in shirt pocket • Used by merchants • Introduced to China in early Christian era • Chinese abacus, suan pan, born in 11th century

  4. The History • The use of the Suan Pan spread to Korea and Japan in the 15th century • Called the Soroban • Changed over time with the final (1850) taking away one bead from both the top and bottom

  5. Today • Abaci are still in use today • The blind are able to make calculations by feel • Merchants and bankers still depend on their abacus for day-to-day business • Asia • Middle East • Africa

  6. How To Use: Place Value • Place Value • Each column represents a place value • Starting at the farthest right is the 1’s, then 10’s, 100’s, so on. • So 236 is represented like: • Now you try… • 9 • 12 • 372 • 5,065 http://www.mandarintools.com/abacus.html

  7. How To Use: Simple + / - • Simple Addition & Subtraction • Always work from LEFT to RIGHT • Example: 237 + 152 • Example: 187 - 125 = 389 • Now You Try! • 1 + 3 = • 12 + 31 = • 123 + 321 = • 9 – 6 = • 43 – 12 = • 263 – 142 = = 62

  8. Complementary Numbers In the case of 5: 4 & 1 3 & 2 In the case of 10: 9 & 1 8 & 2 7 & 3 6 & 4 5 & 5 Examples: 4 + 8 = 12 The complementary number for 8 with respect to 10 is 2. Therefore, subtract 2 from 4 and carry 1 to tens How To Use: Complements

  9. How To Use: + / - with Complements • Adding • Subtract the complement • Examples: • 4+7 = • 2+9 = • 3+8 = • Subtracting • Add the complement • Examples: • 10-7 = • 15-8 = • 17-9 =

  10. Speed: Combining Finger Movements • Using thumb & index finger – pinch beads together (1 “heaven” bead and 3 “earth beads” to create 8) • Using thumb & index finger – push beads simultaneously (3 “earth” beads from ones place and 1 “earth” bead to tens place to add 7) • Examinations – 10th level (easiest)  1st level (most difficult) • Speed ~ What do you think is faster? http://www.youtube.com/watch?v=yj7XbnYrIk0

  11. Crazy but True… • http://www.youtube.com/watch?v=Px_hvzYS3_Y

More Related