Question 251902
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Even numbers are divisible by 2, odd numbers are not.  Of the numbers 1 to 1000, half of them are odd, so half of them are not divisible by 2.


Numbers that end in either 5 or 0 are divisible by 5.  Of the 500 odd numbers in the range 1 to 1000, none of them end in 0 because any number that ends in 0 is even.  All 500 of those odd numbers end in 1, 3, 5, 7, or 9, evenly distributed, so one-fifth of them end in 5.


That means that 4/5 of the 500 odd numbers is not divisible by either 2 or 5.



John
*[tex \LARGE e^{i\pi} + 1 = 0]
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