Euler Problem 16 – Power digit sum

Power digit sum

Problem 16

215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.

What is the sum of the digits of the number 21000?

I don’t know why this has been kept here after such a difficult problem 15. I mean this is simple especially with R. R never had any problem dealing with big numbers. The question is simple need to sum the digits of 2^1000.

I have written a one-line solution 😛

sum(as.numeric(unlist(strsplit(as.character(2^1000), ""))))
#[1] 1366

Here, I calculate 2 raise to 1000 th power, convert it into character, split each character separately, convert them into number and then sum them and boom – THE ANSWER!

Ok, the only tricky part is you need to run

options(scipen = 999)

before running the one-liner. This ensures that 2 ^ 1000 which is a 32 digit long number is represented as it is in complete number if this command is not run it will represent this number in scientific notation which would be something like 1.071509e+301 and then when you convert it into character and sum it , it would return NA’s.


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