In 54, the second digit is 4, and the first digit is 5.

Therefore, 4²+5

=16+5

=21

Similarly, 1²+2

=1+2

=3

Similarly, 3²+0

=9+0

=9

Similarly, 9²+0

=81+0

=81

Similarly, 1²+8

=1+8

=9

Thus, you will get the answer as 9.

0 votes

What is the next number of the following sequence - 54, 21, 3, 9, 81, ??

+2 votes

0 votes

first num is -54. adding the digits gives 9 whch is the 4th num. 2nd num is 21, adding the digits gives 3 whch is the 3rd num. now, following the same order frm the left side(-54,21,3, 9,81,12) as shown the gap, adding the first num i.e. 21 (frm left syd) gives 3 whch is the 4th num(frm left syd). adding the 2nd num(frm lft syd) i.e. 81 gives 9 whch is the 3rd num(frm left syd)

...