How do I view the full Suica card number to link to JR Shinkansen reservations?

Hi Rachael. You need to download the "Suica Finance" app. When that downloads, open it and you should see your Suica card, balance and the full number. It's in Japanese but the number should be on the top right of the landing screen.

If the card is yours the physical copy may still be available to you. Please look up in it.