Web Developer / JAVA SCRIPT Custom Calculator Creation for Webiste

Hello, I need a JAVA script developer to create custom codes based on a different filed calculation and being able to stored the data
And SQL as well

BIRTH Day calculator on my website for numerology and based on a different result sending specifical email.

The formula will look like this. For example, let's imagine:
Your Birth Day, Month, Year will be 7.10.1991
Current Day, Month, Year will be 1.12.2020
I need to 7 + 10 + 2020 = Must count like this 7+1+0+2+0+2+0 =12 1+2=3
So the [result will be 3]
That will be on a first offer - sending an email with the info attached to number 3

On a full formula will be calculation look like this
Then 3+12 = 3+1+2= [6 result}
Then 6+1=[7 result]
Upsell to more detailed reading and >
After on the next page, I need to pick a picture from 9 variations and show it to them

If this is something you think you able to create code or whatever needed to make this happen, please contact me!
The job will be paid based on hours or if you have a specific number based on a project let me know how much is it.
Thank you