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A year is a leap year if:

1. It is divisible by 4
2. BUT if divisible by 100, it must also be divisible by 400

Examples:

• 2024 is a leap year (divisible by 4)
• 2000 is a leap year (divisible by 400)
• 1900 is NOT a leap year (divisible by 100, but not 400)
• 2023 is NOT a leap year (not divisible by 4)