What is the total number of ways in which you can select 4 letters from the word EXAMINATION. (Note - They need not be distinct, e.g. AAEM is possible)

Make Cases Accordingly:
2 same 2 same (AAII AANN IINN)=3
2 same 2 diff (7C2x3=63 eg AA_ _. II_ _ and NN_ _)
All diff (8C4=70)
3+63+70=136

10C4 ?

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https://www.doubtnut.com/question-answer/find-the-number-of-ways-of-selecting-4-letters-from-the-word-examination-643477453

The answer is 136.