So she used 5/6 of the cord to make necklaces.
1 - 5/6 = 1/6
She splits the 1/6 length into 4 equal lengths.
To divide a fraction by a fraction, you multiply it by its reciprocal.
1/6 (1/4)
= 1/24
She used 1/24 of the original chord to make each bracelet.