Random number 1–75

Seventy-five balls is American bingo. The card is five by five, the free space sits in the middle, and each column draws from its own block: B is 1–15, I is 16–30, N is 31–45, G is 46–60, O is 61–75.

That column structure is why a plain 1–75 draw is not a bingo simulation. A caller pulls balls without replacement from one cage, and the card constrains which numbers can appear in which column.

As a straight seventy-five-way pick, though, it is exact: 1.33 percent per number, no ball favoured over another.

Every tap calls crypto.getRandomValues, the browser's cryptographic generator, and asks it for one unsigned 32-bit value. That lands somewhere between 0 and 4,294,967,295, and it then has to be folded down to the 75 numbers in this range.

Folding it down with a plain remainder is where most generators go wrong, an error known as modulo bias. 75 does not divide 4,294,967,296 evenly: 46 values are left over at the top, and wrapping them around would make the first 46 numbers in the range fractionally likelier than the rest. This tool throws away any raw value at or above the last exact multiple of 75 and draws a fresh one instead. That is rejection sampling. It fires about 1 in 93,368,854 draws, and it is the difference between 1.33% exactly and 1.33% approximately.

Ask for more than one number and the tool keeps drawing until it holds that many distinct values, then sorts them ascending. Nothing is seeded, nothing is sent anywhere, and each draw is independent of the one before it. The roll history under the tool lives in your browser's local storage, where the clear button empties it. The daily lucky numbers elsewhere on this site work the opposite way on purpose: they use a seeded generator so the same date always returns the same set. How random is random sets the two side by side.

The B-I-N-G-O columns mean the numbers on a card are never a plain sample of 1–75; each column holds five drawn from its own fifteen. If you are building a card rather than calling a ball, run five draws of 1–15, then 16–30, and so on through the blocks. And unlike a caller's cage, this draws with replacement, so taps are independent and a number can come up twice.