First, select the cells in question, and click the "Number Format" dialog box icon in the bottom-right corner of the Number ...

Extreme heat is impacting states across the country. See maps of high temperature forecasts and heat index levels.

A heat dome is expected to roast more than 30 US states and affect 100million Americans through next week.

Heat dome will cause dangerously high temperatures in many places across the country this weekend, especially the Midwest and East Coast.

To help prepare Americans for the dangerous temperatures, the National Weather Service and the US Centers for Disease Control and Prevention has a national forecast predicting heat-related risks.