Number of words that can be formed using all the letters of the word “REGULATIONS” such that G must come after R, L must come after A and S must come after N is

Word “ REGULATIONS “ has 11 different letters G, R have specified order, L, A have specified order and S, N have specified order. (G,R,L,A,S, N are all different)

$\therefore$No.of arrangemens $=\frac{\mathrm{\angle }11}{\mathrm{\angle }2\cdot \mathrm{\angle }2\cdot \mathrm{\angle }2}$

$=11\times 10\times 9\times \mathrm{\angle }7=990\times \mathrm{\angle }7$