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HKIMO 2026 Grade 6 National Preliminary Set 04 Question 9

HKIMO · HKIMO 2026 Grade 6 National Preliminary Set 04

Question 9

Find $P=1\times 2+2\times 3+3\times 4+\cdots+29\times 30$.
  1. 9990
  2. 8990
  3. 8890
  4. 8880