Question Number 157329 by MathsFan last updated on 22/Oct/21

$$\:\boldsymbol{{whats}}\:\boldsymbol{{the}}\:\boldsymbol{{value}}\:\boldsymbol{{of}}\: \\ $$$$\:\:\:\:!\mathrm{5} \\ $$
Answered by puissant last updated on 24/Oct/21

$$!\mathrm{5}=\mathrm{5}!\left(\frac{\mathrm{1}}{\mathrm{0}!}−\frac{\mathrm{1}}{\mathrm{1}!}+\frac{\mathrm{1}}{\mathrm{2}!}−\frac{\mathrm{1}}{\mathrm{3}!}+\frac{\mathrm{1}}{\mathrm{4}!}−\frac{\mathrm{1}}{\mathrm{120}}\right)=\mathrm{5}!\left(\frac{\mathrm{1}}{\mathrm{2}}−\frac{\mathrm{1}}{\mathrm{6}}+\frac{\mathrm{1}}{\mathrm{24}}−\frac{\mathrm{1}}{\mathrm{120}}\right) \\ $$$$=\:\mathrm{5}!\left(\frac{\mathrm{60}}{\mathrm{120}}−\frac{\mathrm{20}}{\mathrm{120}}+\frac{\mathrm{5}}{\mathrm{120}}−\frac{\mathrm{1}}{\mathrm{120}}\right)=\:\mathrm{120}×\frac{\mathrm{44}}{\mathrm{120}}\:=\:\mathrm{44}.. \\ $$
Commented by MathsFan last updated on 22/Oct/21

$${thank}\:{you}\:{sir} \\ $$$${can}\:{this}\:{also}\:{be}\:{the}\:{answer}\:\left(\frac{\mathrm{5}!}{{e}}\right)=\mathrm{44}.\mathrm{146} \\ $$
Commented by puissant last updated on 22/Oct/21

$${yesss}\:\left(\frac{\mathrm{5}!}{{e}}\right)\:=\:\left(\frac{\mathrm{120}}{{e}}\right)\:=\:\mathrm{44},\mathrm{14} \\ $$
Commented by puissant last updated on 22/Oct/21

Commented by MathsFan last updated on 22/Oct/21

$${thank}\:{you}\:{senior} \\ $$
Commented by puissant last updated on 22/Oct/21

$${De}\:{rien}.. \\ $$
Commented by MathsFan last updated on 22/Oct/21

$${merci}\:{beaucoup} \\ $$
Answered by soumyasaha last updated on 22/Oct/21
![= Subfactorial 5 [No. of derangement] = ⌊((5!)/e) + (1/2) ⌋ = ⌊44.146 + 0.5 ⌋ = ⌊44.646 ⌋ = 44](https://www.tinkutara.com/question/Q157378.png)
Commented by MathsFan last updated on 22/Oct/21

Commented by mr W last updated on 23/Oct/21

Commented by mr W last updated on 23/Oct/21

Commented by MathsFan last updated on 25/Oct/21
