app/views/sign_up_sheet/_micropayment.html.erb
<% found_in_slots = false %>
<% @slots_filled.each do |slot| %>
<% if slot.topic_id.to_s == topic.id.to_s %>
<td align="center"><%= topic.micropayment %></td>
<% found_in_slots = true %>
<% end %>
<% end %>
<% unless found_in_slots %>
<td align="center">0</td>
<% end %>