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Question 1028411: Could someone please check these and tell me if my answers are correct? I would appreciate it very much, I don't feel confident with my answers!
1) Find the sum of all of the 3-digit positive integers.
my answer: (999(99+1))/(2) - (99(99+1))/(2)
(999(1000))/(2) - (99(100))/(2)
(999(500)) - (99(50))
499500 - 4950 = 494550*****
2) Find the sum of every integer from 1 to 1000 that is not a perfect square.
my answer: ((1000)(1000+1))/(2)
(500)(1001)
500500*****
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! 1) Find the sum of all of the 3-digit positive integers.
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The sum from 100 to 999 = 900 integers
Add 450 pairs:
100 + 999 = 1099
101 + 998 = 1099
etc.
450*1099 = 494550
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my answer: (999(99+1))/(2) - (99(99+1))/(2)
(999(1000))/(2) - (99(100))/(2)
(999(500)) - (99(50))
499500 - 4950 = 494550*****
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2) Find the sum of every integer from 1 to 1000 that is not a perfect square.
my answer: ((1000)(1000+1))/(2)
(500)(1001)
500500*****
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That's the sum of all integers.
You have to subtract all the perfect squares.
1,4,9,16, etc up to 961
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