Shell(zsh) exercises: print n fibos, is prime and print n primes; CN Homework

prime-check.sh

#!/bin/zsh

echo "Hey $USER, please enter a number: "
read NBR
CHECK=2
IS_PRIME=1

while [ $CHECK -lt `expr $NBR / 2` ]
do 
	if [ `expr $NBR % $CHECK` -eq 0 ]
	then
		IS_PRIME=0
		break
	fi
	CHECK=$((CHECK+1))
done

if [ $IS_PRIME -eq 1 ]
then
	echo "Your number is prime!"
else
	echo "Your number is not prime! :("
fi

print_n_fibos.sh

#!/bin/zsh

echo "How many numbers do you want me to print? ans: "; read n

if [ $n -lt 1 ]
	then
	echo "You must be retarded"
	exit
fi

last1=1
last2=1

if [ $n -eq 1 ]
then
	echo "1"
	exit
fi

echo "1\n1"

for i in `seq 3 $n`
do
	last2=$((last2+last1))
	last1=$((last2-last1))
	echo $last2
done

print_n_primes.sh

#!bin/zsh

echo "How many primes do you want me to print?"; read nbr_primes

if [ $nbr_primes -lt 1 ]
	then
	echo "Wrong number mate :("
	exit
fi

prime_nbr=2
for i in `seq 1 $nbr_primes`
do
	
	while [ true ]
	do
		checker=2
		prime=1
		while [ $checker -le `expr $prime_nbr / 2` ]
		do
			if [ `expr $prime_nbr % $checker` -eq 0 ]
				then
				prime=0
				break
			fi
			checker=$((checker+1))
		done
		if [ $prime -eq 1 ]
			then
			echo $i": "$prime_nbr
			break
		fi
		prime_nbr=$((prime_nbr+1))
	done
	prime_nbr=$((prime_nbr+1))
done