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Problem of the Day

Friday, September 18, 2026

Problem:

The formula for determining the temperature in degrees Celsius based on a given value in degrees Fahrenheit is

Which of the following instructions, given the double value F, correctly performs that calculation?

  1. double C = 5/9 * F - 32;
  2. double C = (5/9) * (F - 32);
  3. double C = double(5/9) * (F - 32);
  4. double C = 5.0/9 * (F - 32);

Show solution:

The correct answer is d.

When performing division, Java will do an integer division if the operands (5 and 9 in this case) are integers, and 5/9 would be calculated as 0 (9 goes into 5 zero times with a remainder of 5). Answer (c) tries to convert that result to a double value, but not until after the 0 has already been calculated. Answer (d) gets around this issue by specifying that one of the values in the division is a double. Java then performs a division with a double result, which is what we need to successfully perform the conversion.