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Q: Number of digits in equation ( Answered 5 out of 5 stars,   0 Comments )
Question  
Subject: Number of digits in equation
Category: Science > Math
Asked by: mrsneaky-ga
List Price: $2.00
Posted: 29 Apr 2003 20:35 PDT
Expires: 29 May 2003 20:35 PDT
Question ID: 197298
How many digits are in value of 16^360,000 and 2^90,000 and 2^40,000?
Answer  
Subject: Re: Number of digits in equation
Answered By: secret901-ga on 29 Apr 2003 21:30 PDT
Rated:5 out of 5 stars
 
Hi mrsneaky,
The number of digits in an integer is the floor of its log base 10
plus 1 where the floor of a number n is the largest integer smaller or
equal to n.   For example:
the number of digits in 3938 = 4 = floor(log(3938)) + 1

Thus, the number of digits in 2^40,000 would be equal to 
floor(log (2^40,000)) + 1
Using a simple change of base formula, which you can find in the links
below, we can convert log (2^40,000)) to log base 2 (let's denote that
by lg)
log (2^40,000) = (lg 2^40,000)/(lg 10)
               = 40,000/lg 10
               = 40,000/3.321928
               = 12,041.2
Thus, floor(12,041.2) + 1 = 12,042

Similarly, the number of digits of 2^90,000 is
  floor(90,000/3.321928) + 1
= floor(27,092.7) + 1
= 27,093

The number of digits in 16^360000 = 2^(1,440,000) is:
  floor(1,440,000/3.321928) + 1
= floor(433,483.2) + 1
= 433,484

I have calculated the values of 2^40,000 and 2^90,000 exactly using
Scheme to check my answers.  If you're interested, you can view them
at:
http://www.geocities.com/secret901/40000.txt and
http://www.geocities.com/secret901/90000.txt
I hope that answered your question, if you need any clarification,
please request for it before rating this answer.
secret901-ga

Search strategy:
I used my personal knowledge in this subject.

Links:
Changing the base of a logarithm
http://www.sosmath.com/algebra/logs/log4/log43/log43.html
mrsneaky-ga rated this answer:5 out of 5 stars
GREAT THANKS!!!

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