There are two square scale. That is, it has marking where there are square i.e marking at 0,1,4,9,16,25 and so on. When one scale is moved, it slide over the other. Now if one scale is moved odd number i.e say 123 , that is, it's zero is placed at 123 over the other scale, now. Now, can one know, if the squares on the two scales meet more than once??? Atleast twice because for every odd number there will always be two consecutive square whose gap is an odd number i.e 123 is gap between squares 61 and 62. So square 62 in one scale will meet at 61 square on the other scale that is moved. Thanks.