Whilst the new statutory requirements for Year 4 concentrate on developing written methods of addition there are still many important mental skills to develop and re-inforce. These include quick mental addition of three small numbers and the addition of two 2-digit numbers mentally.
A technique which is particularly important is adding the nearest whole ten and adjusting. An example of this can be seen when adding 47 and 38. An easy way to do this is add 47 and 40 making 87 and then adjusting by subtracting 2 to make 85. Done! This is probably an easier way than adding the 7 and 8 and then adding the tens.
When adding several small numbers it is always useful to look for pairs that make 10. This works because addition can be done in any order.
For example 7 + 8 + 3 = ? is done easily by adding 7 and 3 to make 10 and then adding the 8 to make 18. By year 4 children should know by heart all pairs of single digits which add up to 10.
Another powerful technique is to use the knowledge that addition and subtraction are the inverse of each other. Knowing the fact that 47 + 38 = 85 immediately gives several other pieces of information, such as 85 – 38 = 47 etc.
We have a wide range of mental addition worksheets for all year groups and have just updated our Year 4 pages; why not take a look now?