• Four countries still use the English measurement system
  
• All other countries use the Metric system
  
• Countries still using English system are:
  United states
  Liberia
  Myanmar
  United Kingdom (Note: While UK’s official system is Metric, there are still some English units routinely used such as “pint” to measure ale)

-To illustate the point the following interactive map shows the four ‘English Unit’ countries (note: this map was made with r embedded code which is shown)

library(leaflet)
coord<-data.frame(lat=c(37.0902, 55.3781, 6.4281, 21.9162 ), 
                  lng=c(-95.7129, -3.4360, -9.4295, 95.9560))
names=c("United Statess", "United Kingdon", "Liberia", "Myanmar")
coord %>% leaflet() %>% addTiles()   %>%  
                addMarkers(label = names, labelOptions = labelOptions(noHide = TRUE,textsize = "20px"))

• The USA has the largest economy in the word, UK is number 5
• Significant part of US economy is export based, so Americans travel worldwide
• British citizens as well travel extensively
  
• When COVID travel restricions are lifted, many in these four countries will start traveling and they will need a units converter (because it has been so long since they have had to translate units)

• English to Metric Conversation Shiny App
• The math behind the App is very straight forward, here is the server function:

shinyServer(function(input, output) { output\(km <- renderText(input\)miles1.6094) output\(m <- renderText(input\)feet.3048) output\(cm <- renderText(input\)inches*2.54) })

• This App is a simple, straight forward, and easy to use