# Number - Addition and Subtraction Add numbers with up to 3 digits (Year 3) / 4 digits (Year 4) using formal written methods of columnar addition

Sometimes it is useful or necessary to use columnar ("column") addition.   This method is very good for larger problems or to check your calculations.

When writing down problems, separate the numbers into ones (also known as "units"), tens, hundreds and thousands. List the numbers in a column and always start adding with the ones ("units") first. Although the order of the numbers doesn't matter here (38 + 93 will be the same answer as 93 + 38) it is a good idea to get into the habit of putting the larger number at the top (this will be useful for columnar subtraction). If you estimate before you begin you will have a good idea whether or not your answers are correct.  It is useful to check your calculations using the inverse operation too.

If you would like a reminder about addition (or subtraction) have a look at these BBC Bitesize videos. Confident?   Why not try these tasks?

Year 4: As an additional task could you use the code numbers to send a message for somebody else to solve?    Top