it is comparision of bitcoin with digital number because its price increases like a digital number varying thats why called bitcoin is a digital gold.
I do not agree with this comparison because:
1) There is a lot of difference in the pace with which price of gold and bitcoin grows.
2) When we compare from security point of view, it is hard to keep gold safe from hackers or thief.
3) Even from ease of convenience, these two do not match.