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What is the units digit of the sum of the squares of the first 2007 odd, positive integers?

 Feb 1, 2020
 #1
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+1

The formula for the squares of ODD numbers is:

 

n(2n+1)(2n-1)/3  = 

2007*(2*2007 +1) * (2*2007 - 1) / 3 =10,779,058,455

 Feb 1, 2020
 #2
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What is the units digit of the sum of the squares of the first 2007 odd, positive integers?

 

1^2=1

3^2=9

5^2=25

7^2=49

9^2=81

1+9+5+9+1 ..... 25

last digit of the sum of the squares of numbers lesss than 10 = 5

2000/10=200

200*5=1000

so

1+9+25 = 35

 

Thge last digit will be 5

 Feb 2, 2020

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