Something

clear;
while [ 1 = 1 ]; do


num1=$((RANDOM%13+0))
num2=$((RANDOM%13+0))
sign=$((RANDOM%4+0))
read -p $num1'x'$num2= -t 8  ans
let answer=$num1*$num2
cor=$(expr $ans = $answer)

if [ $cor = '1' ];
then printf "\nCorrect." 
else printf "\nWrong, the correct answer is "$answer".";
fi;
seconds=$(date '+%S')
let new=$seconds+3

while [ $seconds != $new ];do
   seconds=""
   seconds=$(date '+%S')
done;

clear;

done;