A "decimal fraction" is defined as a fraction which has a base10 denominator such as 10, 100, 1000 and so forth. Rather than base10, "hexadecimals" are based on base16 mathematics. In the base10 system, a combination of only 10 characters, zero through nine, are used. With the hexadecimal base16 system, a combination of 16 characters, zero through nine plus alphabets A through F, are used to represent numerical values. As is generally the case with calculators, converting a decimal fraction to its hexadecimal equivalent is more complicated to work out by hand than it is to figure out with a calculator.
By Hand

Write down the decimal fraction. For example, 5,902 / 10.

Divide the fraction's numerator (top or first number) by its denominator (bottom or last number). The result is the decimal equivalent of the fraction. For example, 5,902 / 10 = 590.2. Drop anything after the decimal point (if applicable). For example, 590.2 becomes 590.

Divide the result by 16. For example, 590 / 16 = 36 with a remainder of 14. The quotient, if greater than 0, must be divided again. Every remainder represents a hexadecimal number according to the following chart. With a remainder of 14, "E" is the hexadecimal number in this example.

Keep dividing the quotient by 16 until the result is less than 0. For example, 36 / 16 = 2 with a remainder of 4, and 2 / 16 = 0.125. When the quotient is less than 0, proceed to the next step.

Multiply the quotient by 16. For example, 0.125 * 16 = 2. The product represents a hexadecimal number.

Write the hexadecimal number. In the example outlined, the hexadecimal equivalent of 5,902 / 10 is 24E.
Using the Microsoft Scientific Calculator

Open the "Start" menu, then click "All Programs," "Accessories," then "Calculator" to launch the Microsoft Calculator.

Click the "View" tab and select "Scientific."

Enter the fraction's numerator then press the divide key. For example, enter 5902 and press "/" for division.

Enter the fraction's denominator then press the equal key. For example, enter 10 then press "=" for the result. The result is the decimal equivalent of the fraction.

Click on the "Hex" radio button to convert to decimal to hexadecimal format.
References
 Photo Credit Phil Ashley/Lifesize/Getty Images