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Find the sum of the primes between 100 and 200, inclusive, that are 1 or 2 more than a perfect square.

 Oct 16, 2020
edited by Guest  Oct 16, 2020
 #1
avatar+2141 
-1

Let's start by listing out the perfect squares that are between 100 and 200.

11^2=121

12^2=144

13^2=169

14^2=196

 

Now, let's see if the numbers that are 1 or 2 more than these squares are prime.

121+1=122 NOT PRIME

121+2=123 NOT PRIME

144+1=145 NOT PRIME

144+2=146 NOT PRIME

169+1=170 NOT PRIME

169+2=171 PRIME

196+1=197 PRIME

196+2=198 NOT PRIME


171+197=368

 Oct 16, 2020
 #3
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-1

 

Ruh Roh Cal ... 171 = 9 x 19   :-) 

Guest Oct 16, 2020
 #4
avatar+2141 
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Oopsy, you're right. Lemme fix it. . .thanks for pointing it out! laugh

CalTheGreat  Oct 17, 2020
 #2
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Squares between 100   200  inclusive       100    121   144  169  196

                                                                          101                          197        add them together !       *** edited ***

 Oct 16, 2020
edited by ElectricPavlov  Oct 16, 2020
 #5
avatar+2141 
-1

EP, I think it says "BETWEEN 100 and 200. . ." Doesn't that mean not including 100 and 200?

CalTheGreat  Oct 17, 2020

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