MathCastle
Counting & ProbabilityChallenge

Counting & Probability · Challenge problem

Compute 11⋅2+12⋅3+13⋅4+⋯+19⋅1011 \cdot 2 + 12 \cdot 3 + 13 \cdot 4 + \cdots + 19 \cdot 10.

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