 <p><strong>INPUT:</strong></p> <pre><code>1. walking down the street 2. to go to the store 3. to buy some groceries </code></pre> <p><strong>Use this:</strong></p> <pre><code>.sub(/[a-zA-Z]/){|c| c.upcase} </code></pre> <p><strong>OUTPUT:</strong></p> <pre><code>1. Walking down the street 2. to go to the store 3. to buy some groceries </code></pre>