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.
Limit cell entry to whole numbers or numbers in a given range. 1. Select the range that you will set the numeric value entries, and click the Data > Data Validation. 2. (1) Select the Whole number item from the Allow drop down box. (2) Select one item from the Data drop down box according to your needs.