The American Optometric Association suggests that children should have their first regular eye exam at six months of age. Another vision exam should take place when a child is around two or three years of age when their vision undergoes its most rapid development and vision correction is most effective.
The ISNUMBER function is a quick, easy way to check if a cell contains a number. Our example used the IF function to illustrate how ISNUMBER can be used. If you haven't used IF in a formula before, you can read our lesson on the IF function here.
If you want to test a cell and take some action if the cell is blank (empty), you can use the IF function. In the example shown column D contains a date indicating when a task was completed. In column E, a formula checks for blank cells in column D. If a cell is blank, the result is a status of Open. If the cell contains a value (a date in this case, but it could be any value) the formula assigns status of Closed. The formula in cell E5 is: