The radicals you are shown are ground, enclosure, and mouth. To me, it honestly looks more like beggar + mouth.
Whichever radical composition helps you remember it best is fine.
Your beggar has no head, that could cause some trouble. On the other hand WK itself groups together things that don’t really “have a beggar”. No idea why they chose this radical combination. You can make your own mnemonic.
ok, so you’ll need to create a story to help you associate this with “number”. good luck. why mouth + beggar? maybe because someone is begging for mercy with his mouth because of many whips has received? or so many drinks in the mouth? and the person don’t know a number of the bank… something like that. and also you’ll need to think in mnemonic for ごう as well. actually each kanji here and in your life can have multiples associations. WK also is suggesting theirs. many times i create my own mnemonics in Portuguese for my or for my students.