How to find duplicate numbers in regular expression?

Question

Regular Expressions

Essence of the question: you need to find repeated digits, let's say from 4 or more repeating digits.
Array of digits
1234
1111
2222
1000
Must be found
1111
2222

To find repetitions of a particular number 1, you can use the regular expression '^[1]{4,}$'
I don't want to write separate regular expressions for each of the 9 digits, can I find it through one regular expression?

Answer 1

^(\d)\1{3,}$