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Category: Permutation and Combination

In-the-sequence-of-numbers-1-2-11-22-111-222-the-sum-of-the-digits-in-999th-terms-is-

Question Number 42494 by Tawa1 last updated on 26/Aug/18 $$\mathrm{In}\:\mathrm{the}\:\mathrm{sequence}\:\mathrm{of}\:\mathrm{numbers}\:\:\mathrm{1},\:\mathrm{2},\:\mathrm{11},\:\mathrm{22},\:\mathrm{111},\:\mathrm{222},\:…\:\mathrm{the}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{the}\:\mathrm{digits} \\ $$$$\mathrm{in}\:\mathrm{999th}\:\mathrm{terms}\:\mathrm{is}\:?? \\ $$ Commented by Tinku Tara last updated on 22/Apr/21 $$\mathrm{1st}\:\mathrm{term}\:\mathrm{1} \\ $$$$\mathrm{3rd}\:\mathrm{term}\:\mathrm{11}…

A-general-case-we-have-totally-n-letters-among-them-n-1-times-A-n-2-times-B-n-3-times-C-n-4-times-D-etc-n-1-n-2-n-3-n-4-2-n-gt-n-1-n-2-n-3-n-4-how-many-different-words-

Question Number 107844 by mr W last updated on 13/Aug/20 $${A}\:{general}\:{case}: \\ $$$${we}\:{have}\:{totally}\:{n}\:{letters},\:{among}\:{them} \\ $$$${n}_{\mathrm{1}} \:{times}\:{A},\:{n}_{\mathrm{2}} \:{times}\:{B},\:{n}_{\mathrm{3}} \:{times}\:{C}, \\ $$$${n}_{\mathrm{4}} \:{times}\:{D}\:{etc}. \\ $$$$\left({n}_{\mathrm{1}} ,{n}_{\mathrm{2}} ,{n}_{\mathrm{3}}…

A-three-digit-odd-number-less-than-500-is-to-be-formed-from-1-2-3-4-and-5-If-repetition-of-digits-is-allowed-in-how-many-ways-can-this-be-done-

Question Number 173354 by pete last updated on 10/Jul/22 $$\mathrm{A}\:\mathrm{three}−\mathrm{digit}\:\mathrm{odd}\:\mathrm{number}\:\mathrm{less}\:\mathrm{than}\:\mathrm{500} \\ $$$$\mathrm{is}\:\mathrm{to}\:\mathrm{be}\:\mathrm{formed}\:\mathrm{from}\:\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{4}\:\mathrm{and}\:\mathrm{5}.\:\mathrm{If}\:\mathrm{repetition} \\ $$$$\mathrm{of}\:\mathrm{digits}\:\mathrm{is}\:\mathrm{allowed},\:\mathrm{in}\:\mathrm{how}\:\mathrm{many}\:\mathrm{ways} \\ $$$$\mathrm{can}\:\mathrm{this}\:\mathrm{be}\:\mathrm{done}? \\ $$ Commented by pete last updated on 10/Jul/22…

Question-42106

Question Number 42106 by rahul 19 last updated on 18/Aug/18 Answered by tanmay.chaudhury50@gmail.com last updated on 18/Aug/18 $$\mathrm{5}{c}_{\mathrm{2}} ×\mathrm{2}!+\mathrm{5}{c}_{\mathrm{3}} ×\mathrm{3}!+\mathrm{5}{c}_{\mathrm{4}} ×\mathrm{4}!+\mathrm{5}{c}_{\mathrm{5}} ×\mathrm{5}! \\ $$$$=\mathrm{5}{p}_{\mathrm{2}} +\mathrm{5}{p}_{\mathrm{3}}…

How-many-words-can-you-form-using-the-letters-in-UNUSUALLY-such-that-no-same-letters-are-next-to-each-other-Answer-10200-

Question Number 107451 by mr W last updated on 11/Aug/20 $${How}\:{many}\:{words}\:{can}\:{you}\:{form}\:{using} \\ $$$${the}\:{letters}\:\:{in}\:\boldsymbol{{UNUSUALLY}} \\ $$$${such}\:{that}\:{no}\:{same}\:{letters}\:{are}\:\:{next} \\ $$$${to}\:{each}\:{other}? \\ $$$$ \\ $$$$\left[{Answer}:\:\mathrm{10200}\right] \\ $$ Commented by…