Prompting for grades, with confirmation if a score higher than 100 is entered
The only option is this one:

// ...
while (score != -1) {
    if (score &gt; 100) {
        cout &lt;&lt; endl &lt;&lt; "Is the score correct? (Enter 'y' or 'n'): ";
        cin &gt;&gt; decision; cout &lt;&lt; endl;
        if (decision != 'y' &amp;&amp; decision != 'Y') score = 0;
    }

    totalPoints += score;
    cout &lt;&lt; "Next score ('-1' to stop): ";
    cin &gt;&gt; score;
}   //end while
// ...


It can't be more efficient using given circumstances.