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582
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avatar+18 

(1! + 2! + 3! + 4! + ... + 100!)  / 36  ; What is the remainder of this division?

 

I found 9 via the calculator, but how can i solve this problem without being too harsh on it... :( I can't believe i just tried to calculate it on the calculator but if there's a formula or something it will really help me. :) 

 

Thanks!
 

 Jul 27, 2016

Best Answer 

 #3
avatar+118659 
+15

A lot of questions seem easy after you see someone else do it.  I quite like questons like this because they make you think about how numbers interact :)

 Jul 27, 2016
 #1
avatar+118659 
+10

(1! + 2! + 3! + 4! + ... + 100!)  / 36  ; What is the remainder of this division?

 

I found 9 via the calculator, but how can i solve this problem without being too harsh on it... :( I can't believe i just tried to calculate it on the calculator but if there's a formula or something it will really help me. :) 

 

Mmm,     36=1*2*3*  6

so from 6! up to 100! there will be no remainders so I am only going to look at

 

(1!+2!+3!+4!+5!)/36 = (1+2+6+24+120 )/36  =  153/36  =  (144+9)/36

 

The remainder will be 9.

 

Can you understand my logic?

 Jul 27, 2016
 #2
avatar+18 
+10

Yes, I got it. Thank you Melody! Next time i'll try to use my mind and think for the short i guess :)

Nefarious  Jul 27, 2016
 #3
avatar+118659 
+15
Best Answer

A lot of questions seem easy after you see someone else do it.  I quite like questons like this because they make you think about how numbers interact :)

Melody  Jul 27, 2016

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