Q.

If the number of words, with or without meaning. which can be made using all the letters of the word MATHEMATICS in which C and S do not come together, is (6!)k, then k is equal to             [2023]

1 5670  
2 945   
3 2835   
4 1890  

Ans.

(1)

In the word ''MATHEMATICS'' there are, 2→M's; 2→A's; 2→T's

Total number of words formed by the letters of the word ''MATHEMATICS'' is ⌊11⌊2×⌊2×⌊2

Number of words in which 'C' and 'S' come together is ⌊10⌊2×⌊2×⌊2×2

Then, number of words in which 'C' and 'S' do not come together is ⌊11⌊2×⌊2×⌊2-2⌊10⌊2×⌊2×⌊2=9×⌊102×2×2

⇒9×10×9×8×7×6!2×2×2=6!×k  (∵Given)⇒k=5670