问题描述:

I'm not 100% sure how to ask this question so please dont mark me down for that.. I will do my best.

how do I work out what range my number falls in?

eg:

`var range = 100;`

var myNum = 320;

Therfore my result would be `300`

as that is the range 320 falls into.

further exampes would be:

`var range = 100;`

var myNum = 190;

result: 100

var range = 100;

var myNum = 864;

result: 800

and lastly:

`var range = 50;`

var myNum = 864;

result: 850

Hope this make sence.

This is the logic you're looking for:

```
var result = range * Math.floor(myNum / range);
```

Replace `Math.floor`

by `Math.ceil`

if you want to find the upper bound of the "range".
The code above is an implementation of:

- How often does
`range`

suit in`range`

? - Multiply the previous result by
`range`

- The final result equals the "number range".

You can also subtract from `myNum`

the modulus of `myNum`

by `range`

:

```
var result = myNum - (myNum % range);
```

`result = myNum - (myNum % range)`

myNum % range means "if I put range in my myNum as many times as I can, what integer will I have left?"

and you can subtract that from myNum and you get your result.