Skip to content / Đến nội dung
ThichHocToan.com

SEAMO 2026 Paper A SET 3 – Self-practice Question 7

SEAMO · SEAMO 2026 Paper A SET 3 – Self-practice

Question 7

Find the value of $1-2+3-4+5-6+\cdots+19-20+21$.
  1. 8
  2. 9
  3. 10
  4. 11
  5. 12