Often when filling in how much something weigh, you have to use a calculator on the side or switch between apps which can be very cumbersome. Other apps have the feature that you can press + - / * in the number field and it calculates the amount for you which is very handy. Example: Let's say you make 4 portions (lunchboxes for work etc). You can then fill in what all of the chicken weigh and press "/ 4" to divide it by 4. The number is updated and you don't have to use other apps or machines at the same time.