Order by number of childrens

[elemention]

How can i order by number of childrens?

ex:
{% for page in page.find(’/blog’).children.order( page.children|length ) %}
{{ page.title|split(’ ')|slice(0, 1)|join }} ^{{{ page.children|length }}}
{% endfor %}

need this
category¹⁰, category⁵, category²