divmod

          <p><%#= t = min %></p>
          <p><%#= hour, t = t.divmod(60) %></p>
          <p><%#= "%02d:%02d" % [hour, t] # => "18:30" %></p>

divmod woring version

            <% @page = Page.last %>
            <% t = @page.hours.to_i * 60 + @page.minutes.to_i %>
            <% hour, t = t.divmod(60) %>
            <%= "%02d:%02d" % [hour, t] %>

sleepcalc time calc attempts

          <div class="row text-center">
          <% @page = Page.last %>
          <p><%#= @page.hours.to_s + " : " + @page.minutes.to_s %></p>
          <p><%= t = @page.hours.to_i * 60 + @page.minutes.to_i # => 1110 mins %></p>

          <%= @page = Page.last %>
          <%= @page.hours.to_s + " : " + @page.minutes.to_s %>

          <p><%#= t = min %></p>
          <p><%#= hour, t = t.divmod(60) %></p>
          <p><%#= "%02d:%02d" % [hour, t] # => "18:30" %></p>
          <p><%#=  t = Time.at(1110) %></p>
          <p><%#= t = Date.strptime("20150307", "%Y%m%d") %></p>
          <p><%#= t = Date.strptime("1110", "%R") %></p>
          <p><%#= t.hours %></p>
          <p><%#= t = Time.new(2017, 08, 07, 18, 30, 00) %></p>
          <p><%#= Time.at(t).strftime("%H:%M") %></p>
          <p><%#= Time.at(t).strftime("%R") %></p>
          </div>