Hi Fauxapple,
wlcome toi the Apple (user-to-user) Community.
Re: "How to dictate number (digit) for Siri to write down".
Seems Siri generally spells the numbers below ten, and writes numerals for larger numbers.
That is the style guide most in use by writers etc.
“numeral four apples” will work as 4 apples in some cases ...
earlier on, others were reporting issues iOS17 on iPhone ...
So, wondering which Mac computer / iPhone / iPad you are using and which OS version is installed.
Also:
whether you are using "Dictation" or using "Voice Control" for Dictation
Eg: In Voice Control you can switch between "Dictation" mode and "Command" mode, and make some customizations: So you can say "Press the key 4" or say "2 3 4" (Siri gets counting right) and "Erase 2 3"
All the best :-)