# vector creation
x <- c("61", "4", "21", "67", "89", "2")
 
# display vector
print(x)
 
# plotting hist
hist(x)

[1] "61" "4"  "21" "67" "89" "2" 
Error in hist.default(x): 'x' must be numeric
Traceback:

1. hist(x)
2. hist.default(x)
3. stop("'x' must be numeric")

x <- c("61", "4", "21", "67", "89", "2")
 
print(x)
res <- as.numeric(x)
hist(res)

# Create data for chart
val <-data.frame("num"=c("77","55","80","60"),
                 "course"=c('DSA','C++','R','Python'))
 
print(val)
hist(val[,1])

  num course
1  77    DSA
2  55    C++
3  80      R
4  60 Python
Error in hist.default(val[, 1]): 'x' must be numeric
Traceback:

# Create data for chart
val <-data.frame("num"=c(77,55,80,60),
                 "course"=c('DSA','C++','R','Python'))
 
print(val)
 
hist(val[,1])