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Category: Permutation and Combination

Find-how-many-number-greater-than-2-500-can-be-formed-from-the-digit-0-1-2-3-4-if-no-digit-can-be-used-more-than-once-

Question Number 16836 by tawa tawa last updated on 26/Jun/17 $$\mathrm{Find}\:\mathrm{how}\:\mathrm{many}\:\mathrm{number}\:\mathrm{greater}\:\mathrm{than}\:\mathrm{2},\mathrm{500}\:\mathrm{can}\:\mathrm{be}\:\mathrm{formed}\:\mathrm{from}\:\mathrm{the}\:\mathrm{digit} \\ $$$$\mathrm{0},\:\mathrm{1},\:\mathrm{2},\:\mathrm{3},\:\mathrm{4}\:\:\mathrm{if}\:\mathrm{no}\:\mathrm{digit}\:\mathrm{can}\:\mathrm{be}\:\mathrm{used}\:\mathrm{more}\:\mathrm{than}\:\mathrm{once}. \\ $$ Answered by mrW1 last updated on 27/Jun/17 $$\mathrm{2}×\mathrm{4}×\mathrm{3}×\mathrm{2}=\mathrm{48} \\ $$…

Question-147876

Question Number 147876 by puissant last updated on 24/Jul/21 Answered by Olaf_Thorendsen last updated on 24/Jul/21 $$\mathrm{On}\:\mathrm{raisonne}\:\mathrm{par}\:\mathrm{recurrence}. \\ $$$$ \\ $$$$\mathrm{On}\:\mathrm{considere}\:\mathrm{la}\:\mathrm{propriete}\:\mathrm{suivante}\:: \\ $$$$ \\ $$$$“\mathrm{Si}\:\mathrm{on}\:\mathrm{retire}\:\mathrm{une}\:\mathrm{case}\:\mathrm{quelconque}…

If-6-x-4-x-then-x-

Question Number 145104 by imjagoll last updated on 02/Jul/21 $$\:\mathrm{If}\:\frac{!\mathrm{6}}{\mathrm{x}}\:−!\mathrm{4}\:=\:!\mathrm{x}\:\mathrm{then}\:\mathrm{x}\:=? \\ $$ Answered by liberty last updated on 02/Jul/21 $$\:\Rightarrow\:\mathrm{265}−\mathrm{9}{x}\:=\:{x}.\left(!{x}\right) \\ $$$${test}\:{x}=\mathrm{5}\: \\ $$$$\Rightarrow\mathrm{265}−\mathrm{45}\:=\:\mathrm{220}\:\wedge\:\mathrm{5}.\left(!\mathrm{5}\right)=\mathrm{5}×\mathrm{44}=\mathrm{220} \\…