This one's older than the internet: type a number into a calculator, flip the whole thing upside down, and certain digits suddenly look like letters. It works because on a seven-segment display, 0 looks like O, 1 looks like I, 3 looks like E, 5 looks like S, 7 looks like L, 8 looks like B, and 4 or 6 can pass for h or g — all upside down.
This one isn't an upside-down trick — it's a numeric code. "143" comes from counting letters: "I" is 1 letter, "love" is 4 letters, "you" is 3 letters. It became shorthand for "I love you" in pager and early texting culture long before smartphones existed, and it's still used today.
Yes — Apple's Calculator app has shipped built into macOS and iOS for decades, with basic and scientific modes (turn an iPhone sideways to unlock the scientific layout). It's a real, first-party Apple app, not a third-party add-on.
Grab our Basic Calculator (works on any device) and try a few of the words above — or see how many new ones you can find on your own.
Sources: Wikipedia — Calculator spelling, Dictionary.com — 17 Calculator Words