Converting JSON to XML doesn't work

I am trying to convert JSON to XML using newtonsoft, but because the left part contains a number and XML cannot have element that starts with a number the conversion fails

Example:

{
   "PLC": {
       "10": 7.6,
       "9": 1.8,
       "4": 11
      }
}

is there anyway to safely convert it? or make it to add a "_" prefix for example to elements that starts with a number?