Take a look at the sentence again:
My grandmother doesn't trust banks, so she has __________ money all over
the house. Once, I pulled an old Reader's Digest off a shelf and
found seven $100 bills stuck between the pages.
The sentence requires the past participle of hide, an irregular verb. Hidden is the past participle.
| Verb | Simple Present | Simple Past | Past Participle |
| hide | hide(s) | hid | hidden |
Hid, the form you chose, illegally combines the simple past with the auxiliary verb has. Before you continue, review the rules for irregular verbs.
Go back to the sentence to try again.