Learn how to find a missing addend when one of the addends and the sum is given. Take off the given addend from the sum to get the missing addend. Our Missing Addend Worksheet 3 and the other missing addend addition worksheets help kids practise column addition. Expand your knowledge in addition in columns by finding the missing addends. Finding missing addend addition worksheets are ideal for first graders and 2nd graders to learn how two addends are added to give the total and how one addend can be found by taking off the given addend from the sum.