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JavaScript JavaScript Numbers The Math Object Random Number Challenge – Two Numbers Solution

Keith Griffin
Keith Griffin
4,833 Points
Posted by Keith Griffin
Keith Griffin
4,833 Points

How are we supposed to figure out the the equation Math.floor(Math.random() *(highNumber - lowNumber) + lowNumber?

The equation makes sense to me after the fact. For example. (Math.floor(.5) *(10-5) +5) = Math.floor(2.5+5) = 7 which is between 10 and 5 but I don't understand how to come to the conclusion to subtract the low number from the high number.

2 Answers

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

This formula isn't quite right. The multiplier should be highNumber - lowNumber + 1, which represents the range of numbers you want. For example, if you wanted a number between 10 and 15, (15 - 10 + 1) gives you 6, which is how many numbers to choose from (10, 11, 12, 13, 14 and 15).

After multiplying (and applying "floor"), you'll have one of 6 values, but starting from 0. Adding in the low value again shifts the range back up into where you want it.

Frederik Dobbener
Frederik Dobbener
2,356 Points
Frederik Dobbener
Frederik Dobbener
2,356 Points

This is a very good explanation and helped me understand it better. Thanks!

Jared Rogers-Martin
Jared Rogers-Martin
1,143 Points
Jared Rogers-Martin
Jared Rogers-Martin
1,143 Points

Loved this explanation on the formula, thanks!