code: function calcSteps (min, max, room, width) {
    var range = max - min
    var i = 0, e
  
    while(true) {
      var e = Math.pow(10, i++)
      if(e > 10000000000)
        throw new Error('oops')
  
      var re = range/e
      var space = width*1.25
  
      if(room     / (re) > space) return e
      if(room*2   / (re) > space) return e*2
      if(room*2.5 / (re) > space) return e*2.5
      if(room*5   / (re) > space) return e*5
    }
  }
docs: must have range, room, and width