Problem: Euler Task 16 - What is the sum of the digits of the number 2^1000?

"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?"

One line:

 ((2 :BigInt) pow 1000).toString.foldLeft(0)(_ + _ - '0')