Prime number checker

PrimeNoV2

#retrive a number between 1 and another value - varUpper

varUpper = 100

puts 'Welcome to Keith\'s Prime Number checker. Do you want to know if a number is prime? Please enter an integer between one and ' + varUpper.to_s + '.'
varTest = gets.chomp.to_i
if (varTest <= varUpper) and (varTest > 1)
	puts 'Thank you. The number you have entered is ' + varTest.to_s + '.'
else
	while (varTest > varUpper) or (varTest <= 1)
		puts 'The number you have entered is not valid. Please enter another number.'
		varTest = gets.chomp.to_i
	end
end

puts varTest.to_s + ' will now be checked to see if it is a prime.'

#test

varDivisor = 2
varModResult = 1

until (varModResult == 0) or ((varDivisor == ((varTest/2)+1)) or (varDivisor > ((varTest/2)+1)))
	varModResult = varTest % varDivisor
	varDivisor += 1
end

#result
	
if (varModResult == 0)
	puts 'Test completed. ' + varTest.to_s + ' is not a prime number.'
else
	puts 'Congratulations! ' + varTest.to_s + ' is a prime number!' 
end