What do we need negative numbers for?
It might seem weird to do calculations with negative numbers. When do we actually use them in day-to-day life?
Measuring temperature is an example from day-to-day life where we use negative numbers.
Look at Example 1 above. The calculation you did there might as well have been an exercise about temperature:
Somewhere in Norway the temperature is °C right now. You know that it will be °C colder the next day. What will the temperature be the next day?
The next day, the temperature will be . This means that °C is °C colder than °C.