The overnight low temperature was -5 centigrade. If the temperature rose 18 degrees during the following day, what was the number of degrees centigrade in that day's high temperature?

18 - 5 = ?

To find the number of degrees Celsius in that day's high temperature, you need to add the change in temperature to the initial low temperature.

The overnight low temperature was -5 degrees Celsius. If the temperature rose 18 degrees during the following day, you can add 18 to -5 to find the final temperature.

-5 + 18 = 13

Therefore, that day's high temperature was 13 degrees Celsius.