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What is the units digit of the sum of  2^2020 + 7^2020

 Oct 16, 2020
 #2
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What is the units digit of the sum of  2^2020 + 7^2020

2,4,8,16,32,64     the pattern for the last digit is   2,4,8,6,  2,4,8,6,   etc 

 

2020=4*505    will end in 6

 

7,49, 343, 2401, 16807, 117649,   the pattern for the last digit is  7,9,3,1,   7,9,3,1,   

so

7^2020 will end in a 1

 

so  2^2020 + 7^2020   will end in    6*1=   6

 
 Oct 17, 2020
 #3
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Very minor typo Melody. It should read: 6 + 1 = 7

 
Guest Oct 17, 2020
edited by Guest  Oct 17, 2020
edited by Guest  Oct 17, 2020
 #4
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Yes you are right, thanks.

 
Melody  Oct 18, 2020

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