To convert square miles to square kilometers, you can use the conversion factor of 1 square mile = 2.58999 square kilometers. Here are the step-by-step instructions to perform the conversion:

Step 1: Write down the given value in square miles that you want to convert to square kilometers. Let’s say you have X square miles.

Step 2: Multiply the value in square miles (X) by the conversion factor of 2.58999 square kilometers per square mile. This can be written as:

X square miles * 2.58999 square kilometers/square mile

Step 3: Perform the multiplication to find the equivalent value in square kilometers. The square mile unit cancels out, leaving you with the value in square kilometers.

Step 4: Round off the result to the desired number of decimal places, if necessary.

For example, let’s convert 10 square miles to square kilometers:

Step 1: X = 10 square miles

Step 2: 10 square miles * 2.58999 square kilometers/square mile = 25.8999 square kilometers

Step 3: The square mile unit cancels out, leaving us with 25.8999 square kilometers.

Step 4: Rounding off to two decimal places, the final result is approximately 25.90 square kilometers.

Therefore, 10 square miles is approximately equal to 25.90 square kilometers.