The letters of the word 'MANKIND' are written in all possible...

$M$

$A$

$N$

$K$

$I$

$N$

$D$

Arranging the letters alphabetically, we get

ADIKMNN

When the word starts with any of the letters A/D/I/K, the number of possibilities$= \dfrac{6 !}{2 !} \times 4 = 1440$

Now when the word starts with MA, then the number of possibilities$= \dfrac{4 !}{2 !} \times 3 = 36$

Now when the word starts with MAN, then the number of possibilities$= 3 ! \times 2 = 12$

Now when the word starts with MANK, then the number of possibilities$= 4$

Hence, rank of the work MANKIND is $1492$