Hintman medal is awful and mislabeled. You can use far more than 100 hints in total and still never obtain that medal.
Here is how to obtain that medal. First you must use up all of your hints so that you have 0 hints. Next, click the plus on the lightbulb, click to get your hint, wait, etc... Now (and never before) will a shopping cart appear bottom-left. Every 20 seconds (realtime, not game time) click that shopping cart to be able to click to wait to get another hint.
Continue doing that until you have 100+ hints stocked up, yes all in one play without refreshing browser as should you refresh you'll then need to completely clear out all hints all the way back to 0 before being able to stock up again because that shopping cart will never appear otherwise.
Once you have 100+ hints, now refresh the browser, and then use 100 hints IN A ROW one right after the other, using a hint, placing the piece, then immediately using the next hint placing that piece, going to the next stage whenever a stage is cleared, etc. Being very careful to do it exactly this way.
Only legit way to get that Hintman medal.