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'How Do You Do It?' printed from http://nrich.maths.org/
This problem is designed to be done in a group. So, ideally, you
need to find three or four other people to work with you.
Firstly, take some time to work on your own to find the answers to
these calculations, without writing anything down. (Although it
would be good to write down the answer itself so you don't forget
$19 \times 24$
$198 + 997$
Half of $57.6$
$3841 - 665.3$
$5.2 \div 4$
$101 \times 16 \times 4$
Now, join together with the other people in your group and focus on
the first question.
Do you all agree on the answer?
Give EVERYONE in the group time to explain how they worked it
As a group, decide whose method you think is most efficient and
Do the same for each of the six questions: give everyone
the chance to explain their own method and then choose
the most efficient for that calculation.
For the final bit of the challenge, you will need a set of these cards
- one set
for the group. Each card has another calculation on it.
As a group, decide on the most efficient method for each of the
What did you decide and why?