* City Maths teacher finds
that MS Excel software calculates ‘wrongly’ the factorials of numbers
greater than 20, advises not to use the software with blind faith
Staff Reporter
The
software giant Microsoft appears to have left a blind spot in the
widely used product MS Excel. A city-based Mathematics teacher Hemant
Ganjre has found out a problem with the software, and has advised users
not to use MS Excel with blind faith while doing calculations.
Ganjre
told ‘The Hitavada’ that MS Excel’s versions of 2003, 2007, 2010, and
2013 calculate ‘wrongly’ the factorials of numbers greater than 20.
“This is a very big mistake and cannot be neglected as factorial or FACT
function is used for higher studies,” he said. Ganjre, who also teaches
Vedic Mathematics, said that he found out the problem with the software
from the number of zeroes at the end of the factorials calculated by
using the software and calculations done manually.
MS Excel is
widely used software. It has many functions like SUM, MAX, MIN, FACT
(factorial) etc. The FACT function returns the factorial of any number.
In higher studies like B Sc and engineering, aeronautics, satelllite
industries, etc factorial has great importance. Factorial of a number is
the product of multiplication of a series of descending natural numbers
from that number till 1. For instance, factorial of 5 will be the
product of 5x4x3x2x1, that is, 120. Similarly, the factorial of 10
(denoted as (10!)) will be the product of 10x9x8x7x6x5x4x3x2x1, that is,
36,28,800.
According to Ganjre, MS Excel shows the factorials up to
20 correctly. After 20, the factorials of further numbers are
calculated ‘wrongly’. For instance, the factorial of 21 is shown as
51090942171709400000 in MS Excel. As per the calculations done by
Ganjre, the factorial of 21 is 51090942171709440000. Similarly,
factorials of 22, 23, 24, 25 also are calculated ‘wrongly’ in MS Excel
while manual calculations show exact results. “Even if we do not use
FACT function, there is mistake in the simple multiplication to multiply
all the numbers in factorial too,” Ganjre said.
There are several
websites for calculation of factorials. These websites also differ in
results produced by FACT function in MS Excel and their calculations
using simple multiplication. Ganjre said that he was trying to get in
touch with Microsoft to inform it about the problem with FACT function
in MS Excel. “For now, I just appeal to the people using MS Excel not to
have blind faith in factorial calculations,” he added.
(Published in 'The Hitavada' CityLine on November 17, 2014)
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