import re
regex = r"""(?x)
\d+ # Digits
\D+ # Non-digits up to...
$ # The end of string
"""
print(re.search(regex, "My value: 56%").group(0))
aW1wb3J0IHJlCnJlZ2V4ID0gciIiIig/eCkKXGQrICAgICAgICAgICAgICAgICMgRGlnaXRzClxEKyAgICAgICAgICAgICAgICAjIE5vbi1kaWdpdHMgdXAgdG8uLi4KJCAgICAgICAgICAgICAgICAgICMgVGhlIGVuZCBvZiBzdHJpbmcKIiIiCnByaW50KHJlLnNlYXJjaChyZWdleCwgIk15IHZhbHVlOiA1NiUiKS5ncm91cCgwKSk=