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VEDIC MATHEMATICS : Arithmetic Operations. T. K. Prasad http://www.cs.wright.edu/~tkprasad. 45 * 63 = (4 * 10 + 5) * (6 * 10 + 3) = 4 * 10 * 6 * 10 + 4 * 10 * 3 + 5 * 6 * 10 + 5 * 3. = 4 * 6 * 100 + 4 * 3 * 10
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VEDIC MATHEMATICS : Arithmetic Operations T. K. Prasad http://www.cs.wright.edu/~tkprasad Arithmetic Operations
45 * 63 = (4 * 10 + 5) * (6 * 10 + 3) = 4 * 10 * 6 * 10 + 4 * 10 * 3 + 5 * 6 * 10 + 5 * 3 = 4 * 6 * 100 + 4 * 3 * 10 + 5 * 6* 10 + 5 * 3 = 24 * 100 + (12 + 30) * 10 + 15 Multiplying Numbers Arithmetic Operations
= 24 * 100 + (12 + 30) * 10 + 15 = 24 * 100 + 42 * 10 + 15 = 1 5 1 2 x 3 0 x 2 4 x x = 2 8 3 5 Multiplying Numbers Arithmetic Operations
Two Digit Multiplication (of Large Digits in terms of Small Digits) using Vedic Approach Method : Vertically and Crosswise Sutra Correctness and Applicability Arithmetic Operations
Alternatively, 100’s complement of d1 d2 (d2≠ 0) is (9 - d1) (10 - d2). HC(35) = 9 10 -3 -5 6 5 HC(11) = 89 HC(35) = 65 HC(94) = 6 100’s Complement 100’s complement of a 2-digit number n is (100 – n). Arithmetic Operations
Method: Multiply 79 * 97 • Write the first number to be multiplied and its 100’s complement in the first row, and the second number to be multiplied and its 100’s complement in the second row. 79 21 97 03 Arithmetic Operations
79 21 97 03 • To determine the 4-digit product: • subtractcrosswise to obtain the left digits • (79 – 03) = (97 – 21) = 76 • and • multiply the complements vertically to obtain the right digits. • (21 * 03) = 63 • 79 * 97 = 7663 Arithmetic Operations
Another Example • 89 * 91 = • 89 11 • 91 09 • 80 99 • 89 * 91 = 8099 Arithmetic Operations
Questions • Why do both crosswise subtractions yield the same result? • Why does this method yield the correct answer for this example? • Does this method always work for any pair of digits? Arithmetic Operations
Proof Sketch • (89 – 9) = (91 – 11) = 80 • Why are they same? • (89 – (100 – 91)) = (89 + 91 – 100) = 80 • (91 – (100 – 89)) = (91 + 89 – 100) = 80 Arithmetic Operations
89 = (100 – 11) 91 = (100 – 9) 89 * 91 = 89 * (100 – 9) = 89 * 100 – (100 – 11) * 9 = 89 * 100 – 100 * 9+ (11 * 9) = 100 * (89– 9) + 99 = 100 * 80 + 99 = 8099 89 = (100 – 11) 91 = (100 – 9) 89 * 91 = (100 – 11) * 91 = 100 * 91 – 11 * (100 – 9) = 100 * 91 – 11 * 100 + (11 * 9) = 100 * (91– 11) + 99 = 100 * 80 + 99 = 8099 Correctness of Product :Two possibilities Right digit [Vertical Product] Right digit [Vertical Product] Left digit [Crosswise Subtraction] Left digit [Crosswise Subtraction] Arithmetic Operations
Another Example • 69 * 88 69 31 88 12 57 372 60 72 • Note that, the product of the 100’s complements has more than two digits (exceeds 100) . However, the weight associated with 57 and 3 is 100, and hence they can be combined. Arithmetic Operations
Yet Another Example • 30 * 21 30 70 21 79 – 49 5530 – 49+55 30 6 30 This approach is validwith suggested modifications but not very useful! Breakdown?! Arithmetic Operations