The range is part of the rule
A random number is only meaningful inside the range that produced it. Picking from 1 through 10 is different from picking from 0 through 10, and both are different from picking decimals between those endpoints. Before generating values, decide whether the endpoints should be included, whether decimals are allowed, and how many values are needed.
This is important for classroom games, simulations, sampling, and quick decision tools. A result cannot be judged fair if the possible values were unclear. If the goal is a single tabletop-style roll, the Dice Roller may be the clearer page because the number of sides and dice are part of the interface rather than hidden inside a custom range.
For classroom picks, write the range on the board before generating the result. That small step prevents arguments afterward about whether zero, the highest number, or a decimal answer was supposed to be possible.
Duplicates can be correct or completely wrong
Whether repeated values are allowed depends on the task. Drawing five random students without replacement should not repeat a student number. Rolling a die five times can repeat the same value because each roll starts fresh. The duplicate setting is not a cosmetic option; it changes the kind of random process being modeled.
For lists, raffles, practice problems, and sampling without replacement, use a setting that prevents repeats when the range is large enough. For simulations of independent events, repeats usually belong. The Probability Calculator can help when the next question asks how likely a repeated or non-repeated outcome should be.
Decimal output needs a rounding decision
Random decimals can create false precision if too many places are shown. A classroom activity may only need one decimal place, while a simulation may need several. Choose the decimal setting before generating values so the list fits the task. Rounding after the fact can also create repeated values, especially when many results are squeezed into a small number of decimal places.
When students read decimal output, place value still matters. A value of 0.7 is not the same as 0.07, and a value near 1 may behave differently from a value near 0 in a probability activity. The place value chart can help younger learners read those decimals before they interpret the random result.
Seeds are for repeating a draw, not making it more random
A custom seed is useful when the same random-looking output needs to be reproduced later. Teachers may use a seed to share the same practice set with a class. Developers may use it while testing. A seed does not make the draw more fair by itself; it makes the sequence repeatable.
If the output will decide something important, record the range, duplicate rule, number type, count, and seed if one was used. Without those settings, the list of generated numbers is hard to audit. The answer is not only the values on the screen. It is the values plus the rule that produced them.
For low-stakes practice, a fresh unseeded draw is usually fine. For a shared worksheet, a test case, or a published example, repeatability can be more useful than surprise.