Hey Everyone I Want answer for this question. Its a very long process spo i am unable to calculate on any calculator or in any program

9^(9^9) = 9^387420489 

let

$$\\y=9^{387420489} \\\\ logy=log9^{387420489}\\\\ logy=387420489log9\\\\$$

$${\mathtt{387\,420\,489}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{9}}\right) = {\mathtt{369\,693\,099.631\: \!570\: \!368\: \!587\: \!876\: \!1}}$$

$$\\logy=369693099.6315703685878761\\\\ 10^{logy}=10^{369693099.6315703685878761}\\\\ y=10^{369693099}*10^{0.6315703685878761}\\\\ y=10^{0.6315703685878761}*10^{369693099}\\\\$$

$${{\mathtt{10}}}^{{\mathtt{0.631\: \!570\: \!368\: \!587\: \!876\: \!1}}} = {\mathtt{4.281\: \!247\: \!828\: \!802\: \!288\: \!2}}$$

$$9^{({9^9})}\approx 4.2812478288022882\times 10^{36969399}$$