To convert 21 degrees Celsius to Fahrenheit, you can use the formula:
°F = (°C × 9/5) + 32.
Substitute 21 for Celsius:
°F = (21 × 9/5) + 32 = 37.8 + 32 = 69.8°F.
So, 21°C is equivalent to 69.8°F. This temperature is typically considered a mild and comfortable room temperature, often found in moderate climates. Converting temperatures between Celsius and Fahrenheit is useful for understanding weather reports, cooking temperatures, or scientific measurements across different regions using either scale.