Year 3 should aim to be able to recognise the following types of sums and work them out mentally in 4 seconds:

+0 +1 +2 +3

-0 -1 -2 -3

doubles (2 +2  –  12 +12)

doubles takeaway ( 8-4    18 -9)

+10

– 10

+9 (compensation  stategy – eg: 9 + 6 = turn the 9 into a 10 add 6 and takeaway 1)

-9 (compensation strategy – eg: 17 – 9 = turn 9 into a 10, turn 17 into 18,

18 – 10 = 8)

doubles plus 1 ( 6 + 7)