What is the sum of the odd integers

?Explanation:

Do **NOT** try to add all of these. It is key that you notice the pattern. Begin by looking at the first and the last elements: 1 and 99. They add up to lớn 100. Now, consider 3 và 97. Just as 1 + 99 = 100, 3 + 97 = 100. This holds true for the entire list. Therefore, it is crucial that we find the number of such pairings.

Bạn đang xem: Sum of arithmetic series

1, 3, 5, 7, and 9 are paired with 99, 97, 95, 93, và 91, respectively. Therefore, for each 10s digit, there are 5 pairings, or a total of 500. Khổng lồ get all the way through our numbers, you will have lớn repeat this process for the 10s, 20s, 30s, và 40s (all the way lớn 49 + 51 = 100).

Therefore, there are 500 (per pairing) * 5 pairings = 2500.

Xem thêm: Phân Tích Hào Khí Đông A Trong Bài Thơ Tỏ Lòng Của Phạm Ngũ Lão

Report an Error

### Example Question #2 : How khổng lồ Find The Answer to An Arithmetic Sequence

A sequence is defined by the following formula:

What is the 4th element of this sequence?

**Possible Answers:**

**Correct answer:**

Explanation:

With series, you can always "walk through" the values lớn find your answer. Based on our equation, we can rewrite

as :You then continue for the third & the fourth element:

Report an Error

### Example Question #1 : Sequences

What is the sum of the 40th và the 70th elements of the series defined as:

**Possible Answers:**

**Correct answer:**

Explanation:

When you are asked to find elements in a series that are far into its iteration, you need khổng lồ find the pattern. You absolutely cannot waste your time trying to calculate all of the values between

and . Notice that for every element after the first one, you subtract . Thus, for the second element you have:For the third, you have:

Therefore, for the 40th và 70th elements, you will have:

The sum of these two elements is:

Report an Error

Tired of practice problems?

Try live online GRE prep today.

Explore Live Online Prep1-on-1 Tutoring Live Online Class 1-on-1 + Class

### All GRE Math Resources

13 Diagnostic Tests 452 Practice Tests Question of the Day Flashcards Learn by Concept

Popular Subjects

SAT Tutors in Washington DC, English Tutors in thành phố new york City, Algebra Tutors in San Francisco-Bay Area, GMAT Tutors in Dallas Fort Worth, LSAT Tutors in San Francisco-Bay Area, ACT Tutors in Chicago, English Tutors in Washington DC, MCAT Tutors in San Francisco-Bay Area, GMAT Tutors in new york City, SAT Tutors in Chicago

Popular Courses và Classes

SAT Courses và Classes in Denver, MCAT Courses & Classes in Chicago, ISEE Courses và Classes in San Diego, Spanish Courses và Classes in Chicago, GMAT Courses & Classes in Los Angeles, SAT Courses và Classes in Chicago, LSAT Courses & Classes in Miami, ISEE Courses và Classes in Denver, Spanish Courses & Classes in Miami, GRE Courses & Classes in Dallas Fort Worth

Popular test Prep

SSAT kiểm tra Prep in Los Angeles, LSAT kiểm tra Prep in Miami, SSAT demo Prep in Seattle, GMAT kiểm tra Prep in Los Angeles, GRE test Prep in Denver, SAT thử nghiệm Prep in Dallas Fort Worth, GMAT demo Prep in San Francisco-Bay Area, SSAT chạy thử Prep in Atlanta, MCAT thử nghiệm Prep in Atlanta, ISEE test Prep in Denver

Report an issue with this question

If you"ve found an issue with this question, please let us know. With the help of the community we can continue to lớn improve our educational resources.

Do not fill in this field

* Your Name:

* Issue Description:

DMCA Complaint

Your Infringement Notice may be forwarded khổng lồ the buổi tiệc ngọt that made the nội dung available or to third parties such as ChillingEffects.org.

Please follow these steps to file a notice:

You must include the following:

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC 101 S. Hanley Rd, Suite 300 St. Louis, MO 63105