Teenty
Number Theory
Level
2
N=999..........................9
220 nine''s are present
Find the sum of the digits of the number N^2
The answer is 1980.
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its a matter of a cycle of nine's if 3 no. of nine's 999^2 = consists of 2 no. nines an 8 and 1 thus if 220 nine's consists of 219 of no. of nines an 8 and 1 summing up = 219(9) + 9 + 1 = 1980