(1)81
(2)16
(3)18
(4)9
(5)27


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I am unable to find any method to solve such type of questions?
Is there any formal and proper method/technique ??[/quote]


for two digit numbers in the form ab

Pn = ab
Sn = a+b

Pn + Sn = ab+a+b

ab+a+b = 10a+b

ab = 9a

b=9

19 follows the rules
so does 29..39....99

9 numbers in total

For 3 digit numbers
abc

Pn = abc
Sn = a+b+c
abc+a+b+c = 100a+10b+c
abc = 99a+9b
abc = 9(11a+b)

for a =1
bc = 99 +9b {not possible}
for a=2
2bc = 198+b

not possible ...

.
.
.
for a=9
9*bc = 891+ 9b
not possible

So, 9 is the answer