As per the .NET format support shown here:
http://stackoverflow.com/questions/11731996/string-format-numbers-thousands-123k-millions-123m-billions-123b
And here:
http://msdn.microsoft.com/en-us/library/0c899ak8%28v=vs.100%29.aspx#SpecifierTh
123456789.ToString("#,##0,") will return "123,457".
123456789.ToString("#,##0,K") will return "123,457K".
kendo.format("{0:#,##0,", 123456789) will return "123,456,789".
kendo.format("{0:#,##0,K", 123456789) will return "123,456,789K".
As per the .NET standard, each trailing comma will round off 3 digits, so 123456789.ToString("#,##0,,M") will return "123M".