Normal sudoku rules apply. Draw a 1-cell-wide loop of orthogonally connected cells, which does not branch or touch itself, not even diagonally. Circled cells are not on the loop, and the digit in a circle indicates how many of the up to 8 surrounding cells are on the loop. For each pair of adjacent digits along the loop, the larger digit is an integer multiple of the smaller digit. The cell with the rectangle is on the loop.