What is the value of the expression 1 - 7 + 2 - 8 + 3 - 9 + 4 - 10 + _______ to 100 terms?

This question was previously asked in
SSC CHSL Tier-I Exam 2022 Official Paper (Held On: 14 March, 2023 Shift 2)
View all SSC CHSL Papers >
  1. -200
  2. -360
  3. -300
  4. -240

Answer (Detailed Solution Below)

Option 3 : -300
Free
SSC CHSL Exam 2023 Tier-I Official Paper (Held On: 02 Aug 2023 Shift 1)
2.6 Lakh Users
100 Questions 200 Marks 60 Mins

Detailed Solution

Download Solution PDF

Calculation:

The given expression alternates between adding and subtracting the numbers 1, 7, 2, 8, 3, 9, 4, 10, and so on.

We can observe that the numbers being added increase by 1 each time, while the numbers being subtracted also increase by 1 each time.

To find the value of the expression to 100 terms, we can group the terms into pairs.

Each pair consists of a positive number and its negative counterpart.

The sum of each pair is always -6 because (-7 + 1 = -6, -8 + 2 = -6, -9 + 3 = -6, and so on).

Since we have 100 terms in total, we can form 50 pairs.

Each pair sums up to -6, so the sum of the 100 terms is:

50 pairs ×  (-6) = -300

Therefore, the value of the expression 1 - 7 + 2 - 8 + 3 - 9 + 4 - 10 + ... to 100 terms is -300.

Option 3 is the correct answer.

Latest SSC CHSL Updates

Last updated on May 28, 2025

-> The SSC has released the SSC CHSL exam calendar for various exams including CHSL 2025 Recruitment. As per the calendar, SSC CHSL Application process will be active from 23rd June 2025 to 18th July 2025. 

-> The Exam Date for the SSC CHSL 2025 will be from 8th September 2025 to 18th September, 2025. 

-> The SSC CHSL is conducted to recruit candidates for various posts such as Postal Assistant, Lower Divisional Clerks, Court Clerk, Sorting Assistants, Data Entry Operators, etc. under the Central Government. 

-> The SSC CHSL Selection Process consists of a Computer Based Exam (Tier I & Tier II).

-> To enhance your preparation for the exam, practice important questions from SSC CHSL Previous Year Papers. Also, attempt SSC CHSL Mock Test.  

Get Free Access Now
Hot Links: teen patti earning app teen patti club apk all teen patti game teen patti yas