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.
The IF function checks whether a condition is met, and returns one value if TRUE and another value if FALSE. 1. Select cell C2 and enter the following function. The IF function returns Correct because the value in cell A1 is higher than 10.