What Comes Ninth?Date: 11/07/2010 at 12:17:21 From: MONA Subject: Sequencing numbers 3, 9, 4, 5, 25, 20, 21, 441. What is the next number? Date: 11/07/2010 at 12:28:42 From: Doctor Ali Subject: Re: Sequencing numbers Hi Mona! Thanks for writing to Dr. Math. See below: 3 -> raise to the second power -> 9 9 -> subtract by 5 -> 4 4 -> add 1 -> 5 Then those three steps start again, beginning from the result of the third operation: 5 -> raise to the second power -> 25 25 -> subtract by 5 -> 20 20 -> add 1 -> 21 And the pattern repeats: 21 -> raise to the second power -> 441 441 -> subtract by 5 -> ... Does that make sense? Please write back if you still have any difficulties. - Doctor Ali, The Math Forum http://mathforum.org/dr.math/ |
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