To convert pounds (lbs) to kilograms (kg), you can use the following step-by-step instructions:

Step 1: Understand the conversion factor

1 lb is equal to approximately 0.45359237 kg. This is the conversion factor we will use to convert pounds to kilograms.

Step 2: Set up the conversion equation

To convert 21 lbs to kg, we can set up the equation as follows:

21 lbs * (0.45359237 kg/1 lb)

Step 3: Cancel out the units

In the equation, the unit “lbs” appears in both the numerator and denominator, so we can cancel it out:

21 * (0.45359237 kg/1)

Step 4: Perform the calculation

Now, we can simply multiply the numbers:

21 * 0.45359237 = 9.52543777

Step 5: Round the result (if necessary)

Since weight is typically rounded to a certain number of decimal places, you may want to round the result. In this case, rounding to two decimal places would give us:

9.53 kg

Therefore, 21 lbs is approximately equal to 9.53 kg.