Computer Science Canada

Proof

Author:  Martin [ Fri Jul 18, 2003 2:50 am ]
Post subject:  Proof

Alright, these are just some mathematical proof questions. The first ones'll be pretty simple, but they'll get progressively more difficult. I'm going to keep this thread clean, so any off topic remarks (pretty much anything that's not a solution) will be deleted.

Alright, first question, for 10 bits (each question will be worth 10 bits more than the previous).

Quote:
Prove that a number ending in 5 ends in 25 when squared.
ex. 35*35 = 1225. Note the 25

Author:  Crono [ Fri Jul 18, 2003 11:01 am ]
Post subject: 

very simple question, first, let us call the number 10x + 5, x can b greater than 9 if u want,

squaring it gets 100x^2 + 100x + 25, obviously it has to end in 25, duh...

Author:  SilverSprite [ Fri Jul 18, 2003 1:07 pm ]
Post subject: 

Thats no faiiiiiir Crono's too smart to do these questions!!!!! My turn to answer it. Let the number be 10a + 5. Squaring this number gives 100a^2 + 100a + 25. The required result.

Author:  Crono [ Fri Jul 18, 2003 2:11 pm ]
Post subject: 

doesnt matter, a question is a question, doesnt matter whoz doin it, bitz plz

Author:  bugzpodder [ Fri Jul 18, 2003 4:19 pm ]
Post subject: 

Darkness still owes me 500 bits... Crono needs harder questions, such as this one: Show that for each prime p, there exists a prime q such that n^p-p is not divisible by q for any positive integer n.

Author:  Crono [ Sat Jul 19, 2003 12:54 pm ]
Post subject: 

500??? wow, tat's quite a few
i'll work at ur question, it mite take a while, i'll c wut i can do
hope other ppl dun get tis b4 me, tat'd make me look bad, heheh Embarassed


: