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