How many positive integers less than 500 can be written as the sum of two positive perfect cubes?
+129839 The largest cube we can use would be 7
And we can pair this with the integers (1 trough 5 cubed)...."6' is too large!!!
So that's 5 numbers right there
And 6 cubed can be paired with integers (1 through 5 cubed) = 5 numbers
And 5 cubed can be paired with (1 through 4 cubed) = 4 numbers, etc.
So we have....
5 + [ 5(6)/ 2 ] = 5 + 15 = 20 numbers
+129839 The largest cube we can use would be 7
And we can pair this with the integers (1 trough 5 cubed)...."6' is too large!!!
So that's 5 numbers right there
And 6 cubed can be paired with integers (1 through 5 cubed) = 5 numbers
And 5 cubed can be paired with (1 through 4 cubed) = 4 numbers, etc.
So we have....
5 + [ 5(6)/ 2 ] = 5 + 15 = 20 numbers
