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Only p&p Quickie (Posted on 2025-04-09)

Without any calculator or log tables, find the value of 5¹¹ - 6

No Solution Yet Submitted by K Sengupta

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another solution

| Comment 3 of 4 |

Start by observing that 5^12-1 has some nice factoring properties.

5(5^11-6)=5^12-30

(5^12-1)=(5-1)(5^2+5+1)(5+1)(5^2-5+1)(5^2+1)(5^4-5^2+1)

(5^12-1)=(4)(31)(6)(21)(26)(601); 601 has 3 digits but 2 of them are easy

*31=124

*6=744

*21=15624

*26=406224

*601=244140624

244140624-29=244140595

244140595/5=5^11-6=48828119

Edited on April 10, 2025, 3:14 am

Posted by broll on 2025-04-10 03:12:36

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