CalculatePagination

 calculateItems() {
  let currentPage = 3; //needs to be get dynamically
  let itemsTotal = 25;

  const maxItemsPerPage = 12;
  const lastPage = Math.trunc(itemsTotal / maxItemsPerPage) + 1;

  let shownFrom, shownTo;
  

  if(currentPage === 1) {
      shownFrom = '1' ;
      shownTo = maxItemsPerPage;
  } else if (currentPage === lastPage) {
      shownFrom = itemsTotal;
      shownTo = itemsTotal;
  } else {
    shownFrom = (currentPage - 1) * maxItemsPerPage;
    shownTo = currentPage * maxItemsPerPage;
  }

  return {
    shownFrom, shownTo, itemsTotal 
  }
},