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Difficulty: 3/102025 IOQM 2025 (Q29)

Find the value of (10 choose 3).

Options:

  • 120

  • B.

    121

  • C.

    122

  • D.

    123

Guide / Hint

Hint 1: Use the combinations formula: for .

Hint 2: Substitute the values: .

Hint 3: Simplify to: .

Solution

Step 1: The formula for combinations (binomial coefficients) is:

Step 2: Substitute and :

Step 3: Simplify the fraction:

So .

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    2025 IOQM 2025 Q29 - Olympiad Math Olympiad Question | Leminno