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'Which Is Quicker?' printed from http://nrich.maths.org/
Natasha from Moorfield Juniors has
answered the first part of this problem. She says:
I thought it would take longer to count in $10$s to $300$
because the numbers were longer.
Idress from Al Ameen school in Dubai
agrees with Natasha but adds that for the question of counting in
We have to add $7$ each time in our head then count so it will
take more time than just counting in ones.
Urara and Andra from Canadian Academy in
Japan sent in good ideas.
Urara and Andra wrote;
It's much easier to work on this with a partner! When you have
timed yourselves and decided about the reasons for your results,
you could invent some examples for yourselves. You could predict
which was going to be quicker and then try them out to test your
$7$ seconds to get to $30$ in ones. $11$ seconds to get
to $300$ by tens so counting by ones to get to $30$ is quicker
$11$ seconds to get to $40$ in ones. $18$ seconds to get to
$4,000$ in hundreds is slower because we normally don't count in
hundreds so it takes longer time. But we count by ones often
I am slower at counting by sevens because we don't use it very
often and we only remember the times table until $7\times12$.
It all helps us to realise that when we are
solving problems we have to keep our mind on what is happening as
well as just looking at the numbers. A lot of folk did the
arithmetic and said that there was no difference. They were looking
at the difference in the number of numbers used. But of course
the numbers were being said in counting and the people above worked
on that idea. Well done!