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Sleep Cycle Calculator

Find the best times to wake up (or go to sleep) based on 90-minute sleep cycles.

A full sleep cycle is about 90 minutes. Waking up at the end of a cycle (rather than in the middle of one) tends to feel more refreshing. Includes ~15 minutes to fall asleep.

Fibonacci Sequence Generator

Generate the Fibonacci sequence up to N terms.

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Perfect Number Checker

Check if a number is a perfect number.

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Armstrong Number Checker

Check if a number is an Armstrong (narcissistic) number.

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Shift Schedule Calculator

Calculate total hours worked across multiple shifts.

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Business Hours Difference Calculator

Calculate working hours between two dates, excluding weekends.

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Marathon Pace Calculator

Calculate the pace you need for a race goal time.

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