Independent trials, not a shuffled pack
This tool repeats the same inclusive integer experiment for every requested position. A range of 1 through 20 contains 20 outcomes on each trial, so a particular value has probability 1/20 each time. Earlier results do not leave the pool: duplicate values are a normal consequence of sampling with replacement.
Worked case: stress-test identifiers
Suppose five mock events need test IDs from 1 to 20 and the result is 3, 17, 3, 9, 20. The second 3 is valid because the fifth trial has the same twenty possible values as the first. That sequence is useful for testing software that must handle repeated IDs; it would be unsuitable for assigning five different seats.
How often a collision is expected
For five draws from twenty labels, the chance that all five differ is 20/20 × 19/20 × 18/20 × 17/20 × 16/20, about 58.14%. Therefore a repeated value occurs about 41.86% of the time. A repeat in a short run is not a malfunction or proof that the generator favours one number.
Boundaries of the model
The result is a sequence, not a permutation and not a weighted simulation. It cannot ensure coverage of every label, make some outcomes more common, or decide whether a repeated record should be rejected. If each recipient must receive a different number, use a without-replacement selection and check that the requested count does not exceed the available labels.
Read a sequence as a sequence
A test log should retain all positions, including repeats, because the sequence can expose collision handling. Replacing the second 3 with another number after the draw silently changes the experiment. If duplicate output is unacceptable, choose the no-repeat rule before generating rather than repairing a result that followed the stated rule.
Questions about this selection rule
Why did the same integer appear twice?
Every position is drawn from the full range again, so no value is retired.
Can five results cover every number from 1 to 20?
No; five trials can show at most five distinct labels.
Is a long streak impossible?
No. Independent draws can produce streaks, although particular long sequences are uncommon.
Other number formats
All number generators · Random Number Generator · Random Decimal Generator