How it works
This random number generator gives decimal results: type any lowest and highest, even negative, and choose 0 to 10 decimal places. Every place always shows, so 7.30 never shrinks to 7.3. Draw up to 1,000, sorted or with no repeats.
Count the values in a setting
Two places means steps of one hundredth. From 0 to 10 that is 1,000 steps, plus one because both ends count: 1,001 values, the count printed under a single result. In general, multiply the width by 10 for each place, then add 1: 1 to 2 holds 101 values at two places and 11 at one.
Worked example: round 7.38 to one place
The line under a result rounds it twice: 7.38 reads 7.4 to 1 decimal place and 7 to the nearest whole number. The rule: look one digit to the right, and 5 or more pushes the kept digit up, so 7.32 stays 7.3. A 9 rolls over: 3.97 becomes 4.0, zero kept. Common Core, adopted by most US states, puts this in grade 5.
Tips
- For one place, set Decimal places to 1. Rounding two-place draws by hand is unfair: five values round to 0.0, ten to 0.1.
- Ordering practice: draw 5, let the class sort them, then set Order to Lowest first. The same values re-sort; nothing is redrawn.
- Draw 100 from 0 to 10 and read the average under the results. About 96 runs in 100 land between 4.4 and 5.6.
Questions and answers
Is every decimal equally likely, even the two ends?
Yes. The page draws a whole-number position, 0 to 1,000 on the opening range, then puts the point in, so 0.00 and 10.00 each come up 1 time in 1,001. The spreadsheet formula =ROUND(RAND()*10,2) gives each end half the chance of the rest.
Can this decimal number generator make test prices?
Yes. Type 0.01 and 99.99, keep two places, open More options and set How many to 50. Leave No repeats off: real prices repeat. Copy keeps every zero, but a spreadsheet shows a pasted 7.30 as 7.3 unless the column is set to two places.
What are the -1 to 1 and 1 to 2 quick settings for?
-1 to 1 gives 201 two-place values centered on zero, the span of a correlation. 1 to 2 gives 101 multipliers from 1.00 to 2.00. For a plain 0 or 1, the random number generator has a one-tap range.