It is rather hard for human brain to figure out all dividers even for a number with 4 digits and almost impossible for bigger numbers without using any calculator or other outer sources.
So i've decided to build "factory" which doesn't need to know dividers as it operates hundreds / thousands / millions etc.
The general idea is to collect all digits from 0 to 9 and multiply it by it's position in number.
So lets start.

Firstly you build 10 storages for your 0-9 digits.


From 1 to 9 you harvest digits direct from source.

For 0 you need to build subtractor machine from any digit, and to subtract it from itself. This logic is exetremely basic and you can build it easily. I did it like this:


Next you have to make multiplicator of 1 - 10 - 100 - 1000 - etc

step 1 is to make 10: simpe factory of 5*2 or any a+b = 10. As easy as make 0. I did it 5*2 but i think that 5+5 will be even simplier solution.


step 2 is make an exponentiator to convert 10 to 100 or 1000 or any multiplicator you want.


Now we have all that is needed for making any number.

As we have gathered all digits we need it is time to build sorting machine using "priority" feature and than combine it with multiplicator of 10^x.

To select digit from 0 to 9 use priority feature:
single sorter for 2 digits looks like this


To perform correctly the flow of digits must be without gaps, otherwise low priority numbers could sneak into next step, and this is not what we want.

To make selection of 0-9 - u just combine 10 of such sorters.


Now you can choose a digit via priority switches. It is time to multiply it!
I used same design as 5*2.


Now it is time to assemble the needed number:

for first digit position you don't need to make 10 and exponentiator and no need for multiplicator, so you have:
0-factory + collect1-9 ---> sorter --->

for second digit positiont you skip exponentiator
0-factory + collect1-9 ---> sorter ---> multiplicator
10-factory ---> multiplicator

for all other positions you have full cycle:
0-factory + collect1-9 ---> sorter ---> multiplicator
10-factory ---> exponentiator --->multiplicator

An you craeate a new block for each next digit. For example to create any number from 0 to 999 999 yo need 6 blocks:

Than you combine it through several simple "adders" like: 1 + 10, 100 + 1000, 10k + 100k, than 11+ 1100, and than 1111 + 110k. If you have more blocks - you will have more adders.


You create blocks with ctrc+c - ctrl+v and then attach them to new sources of 0, 1-9 and 10.

Each piece of block is simple enough to make it your own way, and if you played at least a few hours, you will have all pieces exept sorter. And sorter is the weakest point, as it is the only piece that must have "constant flow" at input, all other elements have no issues with waiting for input.

All examples are for times 3 production. Complete scheme is smth like this and you can expand it as much as you need.



GLHF.


UPD:
block example with 5+5 for "10-factory" after some tweaking


Any 8digit number factory. A little bit long to connect all inputs, but then you need only to switch priorities up to 99 999 999=)