The sum of the odd numbers (from 1) up to to 500 is 62500.
The sum of an arithmetic series is given by:
sum = 1/2 x number_in_series x (first + last)
For the odd numbers from 1 to 500, there is:
number_in_series = 250
first = 1
last = 499
which gives the sum as:
sum = 1/2 x 250 x (1 + 499)
= 62500.
Chat with our AI personalities
There are no such numbers. The sum of any three odd numbers must be odd. 112 is not.
Yes, all you have to do is to count the number of ODD numbers in the list. If it is odd, then the sum will be odd; if even, so will the sum. Knowing this can help you run a quick validity check when you sum up a list of numbers. (The method works because: a) the sum of two even numbers is even, and b) the sum pf two odd numbers is even, but c) the sum of an even number and an odd number is odd. Hence, if you only determine whether there are any unpaired odd numbers, you know the answer.)
25
Well, honey, all you need to do is check the last digit of each number. If there's an odd number of odd digits, the sum is odd. If there's an even number of odd digits, the sum is even. So, in this case, 13 and 17 are odd, and 45 and 24 are even, which means the sum is odd without adding them all up. Easy peasy, lemon squeezy!
It is not possible for five odd numbers to add up to 50 or any even number.