Look at the range of numbers you're trying to add together. If you'd like to use a formula to sum the integers, ensure that the numbers progress in a constant amount.  For example, the series, 5, 6, 7, 8, 9 is a series and so is 17, 19, 21, 23, 25. You wouldn't be able to use 5, 6, 9, 11, 14 because the progression isn't constant. In order to use a formula to find the sum of 1 to n{\displaystyle n}, choose the largest integer to be n{\displaystyle n}.  For example, if you're trying to add all of the integers from 1 to 100, n{\displaystyle n} will be 100 because it's the largest integer in the sequence. As a reminder, integers are whole numbers, so n{\displaystyle n} cannot be a decimal, fraction, or negative number. In order to sum the integers from your starting number to n{\displaystyle n}, determine how many terms you're adding. For example, if you're adding the first 200 integers, you'll have 200 plus 1 to equal 201 integers. If you're adding the first integers from 1 to 12, you'll have 12 plus 1 to equal 13 terms. You may be asked to find the sum of a range of integers between two integers. If you're summing exclusively, you'll need to subtract 1 from your n{\displaystyle n}. For example, if you're finding the sum of the integers from 1 to 100 exclusively, subtract 1 from 100 to get 99.
حدد نوع التسلسل الحسابي. عرّف ن في التسلسل الذي تجمع أعداده. حدد عدد الأعداد الصحيحة التي تجمعها. اعرف ما إذا كنت تجمع الأعداد الواقعة "بين" العددين.