In Year 6, there is not a great deal of new learning in these areas as much of this has been learnt earlier in the school. The numbers that we deal with just get bigger, but the concepts are still the same.

Subtraction

An efficient method for subtraction of larger numbers is the column subtraction method. This video shows what happens in subtraction if you use Base 10 equipment and how this is shown in the formal written method.

Things can start to get a little trickier when there are lots of zeros in the "top number". This video shows exactly what to do.

Subtraction "Hack"

If you were doing the calculation 30,000 - 342 there are a lot of zeros in the calculation and the column method would not be efficient.  However, all this calculation is asking for is the difference between 30,000 and 342.  So if you were to move both numbers by one place to the right along a number line, the distance between them would be the same.  So, you could calculate 29,999 - 341 which would be much easier to do with column subtraction!