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.
Select the cell or range of cells that contains the formula. If the formula is an array formula, you must first select all cells in the range of cells that contains the array formula: Click a cell in the array formula. On the Home tab, in the Editing group, click Find & Select, and then click Go To. Click Special.