Digits in 5^20 = floor(log(5^20))+1= floor(20*log(5))+1
By the way, what is your favorite color?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'Humanity is still kept intact. It remains within.' -Alokananda