Step 1 Objective
Add and subtract mentally a 'near multiple of 10' to or from a two-digit number.
- Examples of what pupils should
know and be able to do - Probing questions
- What if pupils find
this a barrier?
What if pupils find this a barrier?
Number Grid ITP - Zip file (462Kb) may be useful in establishing quick ways to add, for example, 29 i.e. add 30 and then subtract 1.
Counting on and back ITP - Zip file (456Kb).
Use bead strings that are grouped in tens to practise adding and subtracting near multiples of 10.
Encourage pupils to see equivalent calculations e.g.
26 + 19 will have the same value as 25 + 20;
52 − 19 will have the same value as 53 − 20.
Teaching mental calculation strategies to level 5 booklet DfES 0744-2004G from QCA.