If you're seeing this message, it means we're having trouble loading external resources on our website.
If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.
Example: Adding negative numbers
This original Khan Academy video was translated into Xhosa by Luyolo Sijake. The translation project was made possible by the University of Cape Town's OpenUCT Initiative and has been coordinated by a collaboration between Numeric and ClickMaths.