Written methods of Addition
Estimate and Check
Before writing out a calculation it is a good idea to make an estimate first. This is a simple and quick process which helps to ensure that you do not make silly mistakes.
Say you need to add 402 to 97 - simply round the first number 402 to 400, then round the second number 97 to 100 - add the two rounded numbers, 400 + 100 = 500 and you now know that your final answer should be close to 500. When you have completed your calculation, check that it is similar to your estimate and that it makes sense.
This method involves partitioning the numbers into 100's, 10's and units, adding these individually and then combining the results to give a final answer.