10, 29, 40, 18, 20, 15, 5,
4, 3, 35, 41, 14, 30, 12,
36, 9, 31, 42, 27, 11, 25.
Most of the numbers in the list above can be added to another number in the list to give a sum of 45. Which numbers do not have a partner?
Topics: Starter  Arithmetic  Mental Methods  Number
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Previous Day  This starter is for 30 August  Next Day
Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.
Note that you can click on a number to partially hide it. Click it again to show it. This is useful to eliminate all of the pairs to leave only the numbers with no partner showing. The pupil version of this activity is even more interactive. The link is lower down this page.
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