Yes.
Perhaps a bit nicer to read is to combine the conditions:
print("Please enter a number: ")
a=parse(Int,readline())
if (a>=1) && (a<=99)
print("OK")
end
Also note that you don’t need the parenthesis for the condition of the if. For more complex conditions (like in my code), the parenthesis can help increase legibility but for very simple conditions (your code) one typically would omit them:
print("Please enter a number: ")
a=parse(Int,readline())
if a >= 1
if a <= 99
print("OK")
end
end
Finally, for this specific example there are alternative ways of writing the condition (not better by any means I am just showing you some more of the language):
variant1 = a in 1:99
variant2 = 1 <= a <= 99