Short Answer 
Understand weight units such as mass (kilograms) and force (pounds); to convert 90 kilograms, multiply by 2.20462 for pounds (approximately 198.42 pounds) and divide by 6.35029 for stone (approximately 14.17 stone).
Step 1: Understand the Weight Units
Weight can be measured in two main units: mass (kilograms) and force (pounds). In the metric system, mass is typically expressed in kilograms, while in the imperial system, force is commonly expressed in pounds. Additionally, in some regions, weight may also be measured in stone, which is another unit used predominantly in the UK.
Step 2: Convert Kilograms to Pounds
To convert 90 kilograms to pounds, you need to use a conversion factor. The relationship between these units is that 1 kilogram is approximately equal to 2.20462 pounds. To perform the conversion, follow these steps:
- Multiply 90 kg by 2.20462.
- This results in approximately 198.42 pounds.
Step 3: Convert Kilograms to Stone
For converting 90 kilograms into stone, you need to use another conversion factor, where 1 stone equals approximately 6.35029 kilograms. To calculate this, follow the steps:
- Divide 90 kg by 6.35029.
- This gives you approximately 14.17 stone.