Question Number 158050 by MathsFan last updated on 30/Oct/21
$$\:\mathrm{what}\:\:\mathrm{is}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\: \\ $$$$\:\mathrm{9}!! \\ $$
Answered by puissant last updated on 30/Oct/21
$$\mathrm{9}!!\:=\:\mathrm{9}×\mathrm{7}×\mathrm{5}×\mathrm{3}×\mathrm{1}\:=\:\mathrm{945} \\ $$
Commented by MathsFan last updated on 30/Oct/21
$$\mathrm{please}\:\mathrm{how} \\ $$
Commented by puissant last updated on 30/Oct/21
$${n}!!\:=\:{n}\left({n}−\mathrm{2}\right)\left({n}−\mathrm{4}\right)…. \\ $$
Commented by MathsFan last updated on 31/Oct/21
$$\mathrm{thanks} \\ $$
Commented by MathsFan last updated on 31/Oct/21
$$\mathrm{sir},\:\mathrm{what}\:\mathrm{about}\:{n}!!! \\ $$
Commented by puissant last updated on 31/Oct/21
$${n}!!!={n}\left({n}−\mathrm{3}\right)\left({n}−\mathrm{6}\right)…. \\ $$
Commented by MathsFan last updated on 31/Oct/21
$$\mathrm{okay}….\mathrm{understood}\:\mathrm{sir} \\ $$$$\mathrm{thanks} \\ $$