The official Roblox description says the rarest item has a stated chance of 1 in 20 quadrillion. It does not publicly name that item, explain modifiers, or publish a complete rarity table. Treat the line as a headline claim, not a full odds model.
What the Roblox page says
The game description advertises a rarest-item chance of 1 in 20 quadrillion. It does not say whether that is a base chance, a final chance after Luck, shorthand for the UI, or a number tied to one world or event.
Those details would change the meaning, so one sentence is not enough to rebuild the hidden formula.
What the number leaves out
We could not find a full table of coins, loot, rarity labels, base chances, multiplier effects, or world pools. The description also does not name the item tied to the headline. Solar Sun appears in a separate gameplay video, but that does not prove the two are connected.
- The item is not named.
- Base chance versus final chance is not explained.
- Luck and event modifiers are not documented.
- A complete item roster is not available.
How to document a rare result
Capture the item name, visible rarity label, world or fountain, any active event, and the date. A short clip that shows the result in context is stronger than a cropped image. If a future official update publishes a table, use that source instead of continuing to infer from older observations.
The evidence explorer groups entries by their source state so a named observation is not silently promoted into an official ranking.
Why letter grades would mislead
A conventional S/A/B/C list needs comparable entities and a stable criterion. Here, the public sources do not provide costs, effects, odds, sell values, or a full roster. Assigning grades would mainly rank the writer’s guesses. A goal-first evidence list is narrower, but it answers the honest question: what do we know enough to act on?
Common questions
What is the rarest item in Throw a Coin?
The official description does not name it; it only markets a rarest-item chance of 1 in 20 quadrillion.
Is Solar Sun the 1-in-20-quadrillion item?
No reliable public source found in this check proves that connection.
Does Luck change the 1-in-20-quadrillion chance?
The public description names Luck upgrades but does not explain how they interact with that headline number.
Why is there no complete rarity table?
No stable official or reproducible public table was available at the July 21 check.