First, we need to convert the length of the string from centimeters to millimeters since the width of the beads is given in millimeters.
1 centimeter = 10 millimeters
Therefore, 24 centimeters = 24 x 10 = 240 millimeters.
Next, we need to find out how many beads will fit in 240 millimeters of string.
Since each bead is 6 millimeters wide, we can divide the length of the string by the width of each bead:
240 / 6 = 40
So, 40 beads will fit in 240 millimeters of string.
Since Peyton has 100 beads, and she used 40 of them for the necklace, she will have 100 - 40 = 60 beads left over.