check.rb

def check_grade(grade)
  puts "Checking #{grade}"
  case grade
  when 90..100
    puts "A"
  when 80...90
    puts "B"
  else
    puts "loser"
  end
end

check_grade(60)
check_grade(80)
check_grade(84)
check_grade(90)
check_grade(95.6)
check_grade(100)
check_grade(101)

gistfile1.txt

$ ruby tmp/check.rb
Checking 60
loser
Checking 80
B
Checking 84
B
Checking 90
A
Checking 95.6
A
Checking 100
A
Checking 101
loser