Letter on position 1 (c) changed: 10 words basts easts fasts gasts lasts masts oasts pasts vasts wasts Letter on position 2 (a) changed: 3 words cists costs cysts Letter on position 3 (s) changed: 2 words cants carts Letter on position 4 (t) changed: 4 words casas cases casks casus Letter on position 5 (s) changed: 1 word caste