Lock It: Calculator Vault is a calculator that does real math. Type your own secret equation and press =, and it opens a private vault instead. Inside, you can keep photos and videos, notes, passwords and 2FA codes, encrypted with AES-256 on your phone. You can chat and make live video or voice calls with people you invite by key or QR code, and send files up to 1 GB through Encrypted Cloud. Your equation is stored only as a salted hash, so we can't see it. Free with ads. Premium Pro is $4.99 a month, and Offline Vault is a $9.99 one-time purchase. Search "Lock It: Calculator Vault" on Google Play: https://play.google.com/store/apps/details?id=com.appfactory.calculator