Can anyone help me to calculate days using datepicker and add days block

i want to make an app that calculate spesific days and time from datepicker when i use add days, i can’t make it past months, but when i make it months i cant make it past years, can anyone help me, it is calculate 280 days


  1. Try to read the guide share by taifun
  2. If you have tried something , pls show us