It gave me a riddle for the first digit, but I repeated the riddle back to her which she took as the correct answer.
Then a 20 questions quiz for the second digit which was cool, then a series of clues for the last digit, the last of which was "the last digit is the sum of X and y".
Sorry for your loss. It sounds like you had a very close relationship with him that must make it really hard.
I lost my dad 7 years ago last month, and it's been the hardest thing in my life. If it's any consolation for you, you will never stop missing him. This Reddit post really helped me during the really hard times https://www.reddit.com/r/GriefSupport/comments/d9685e/grief_...
You don't have to spy on people to give them relevant ads; you can just match the content on the page rather than their entire history. For instance: If they're on a page for computer hardware, show them computer hardware ads instead of mining the last few years of their search history to decide to show them an ad for soap on that hardware page.