Find sum of digits of:(1999)^1999.
[The final answer should be a single digit number, for example, (2)^16 = 65536 and the sum of its digits will be given by (6 + 5 + 5 + 3 + 6 = 25, which again will be reduced to 2 + 5 = 7].

(In reply to NOOOOOOOOOOOO by Alissa)

Why, Alissa! What's so HARD about it!! You must  look very carefully at Gamer's and Praneeth's respective simple method-oriented solutions and try to understand them!!!

Edited on December 12, 2021, 11:12 pm

Posted by K Sengupta on 2021-12-12 23:10:46