Adding near doubles - numbers less than 20

Duration 01:22

Two friends use a near doubling strategy to work out how many socks they have put into a washing machine. Bernie puts 11 socks into a washing machine. Bill arrives and puts 12 socks into another machine. To work out how many socks they have in total, 11 is doubled and 1 is added to the result to get the answer.

This clip is from:
Numbertime, Patterns of Addition
First broadcast:
30 January 2008

Children could be given sets of counters which are near doubles, for example, a set of seven and a set of eight. They could then identify which of these numbers they would prefer to double, and then adjust the answer accordingly by adding or subtracting one. To extend the activity, numbers could be increased to two-digit ones.