score=0
of=0
clear;
while [ 1 = 1 ]; do
  ans=
  num1=$((RANDOM%13+0))
  num2=$((RANDOM%13+0))
  sign=$((RANDOM%4+0))
  printf "/exit to quit\n"
  read -p $num1'x'$num2= -t 5  ans
  let answer=$num1*$num2
  cor=$(expr $ans = $answer)
  if [ "$cor" = "1" ];
    then printf "\nCorrect.\n" && score=$(expr $score + 1) && of=$(expr $of + 1 ) 
    else printf "\nWrong, the correct answer is "$answer"\n" && of=$(expr $of + 1);
#    elif [ $cor = '/exit' ];
#      then clear 
#      echo "You got $score right."
#      read -p 'Hit enter to exit'
#      exit 0;
#      fi;
    fi;
  printf 'So far you have answered '$score' out of '$of' right.'
  seconds=$(date '+%S')
  if [ $seconds -gt "57" ];
    then let new=$seconds-56;
    else let new=$seconds+4;
    fi;

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

  clear;

  done;