In our last lesson we worked with the "natural" numbers {1, 2, 3....}. Over time, for several reasons, people found a need to move beyond the natural numbers and create the integers. A natural number without a dash in front meant something “positive” (I have 6 sheep to sell), while the same number with a dash in front meant something “negative” (I’ve lost 6 sheep that I could have sold). After this video you'll be able to multiply and divide integers.
An introduction to the integers