
What are random numbers? 
Random number can be generated by a randomizer. This a physical device, a kind of lottery machine, having the following properties:
 The device can be used repeatedly.
 Every time the device is activated, it produces a number in the range from 1 up to and including N. The value N is assumed to be known.
 Every time again each of the possible numbers 1 to N has the same probability of being produced. Knowledge of previous outcomes does not help in predicting the next outcome. In short: every prediction system fails.
Examples of randomizers: a coin (2 outcomes: 1=head, 2=tails), a dice (6 outcomes) and roulette wheel (37 outcomes: 0 to 36).
You can use a 20sided dice to produce randum numbers. One throw of the dice produces a digit in the range from 0 to 9 (if 10 is subtracted from the outcomes 11 to 19, and 20 is interpreted as a 0). For example to produce a number between 1 and 400, throw the dice three times. This gives you a threedigit number. If the value is 0 or over 400, just throw again.



Picking an arbitrary number 
This demonstration shows what happens if you generate random numbers in the range from 0 up to and including 9.You start the demonstration by clicking on the green square adjacent to Start. A series of random numbers is generated. The bar chart shows the frequencies with which the numbers were produced.
If the randomizer is working properly, there will not be much difference between the frequencies. Each bar in the bar chart will approximately have the same length. Suppose you have the impression that one number has a higher frequency. You can always test this hypothesis by repeating the experiment. Most likely, a different number will now have a higher frequency, thereby rejecting your hypothesis.

A randomizer 
You can use the randomizer below to generate random numbers. First enter a lwoer bound and an upper bound for the range of integers you want to draw your number from. After that, you can click the button Draw. After each click, a new random number is produced.

