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'28 and It's Upward and Onward' printed from http://nrich.maths.org/
You may like to have a go at the problem So It's $28$
We are about to explore the number
In $2010$ the month of February will have four weeks of $7$
days making $28$ days altogether.
Half a pack of cards with the jokers makes $28$ cards
The seventh triangular number is also $28$:
But all these examples of $28$ are just flat - or
you might call them $2$D.
I'm suggesting we try making something $3$D.
How about if we put some small cubes
together and count the faces which are visible. Can we arrange the
cubes so that there are exactly $28$ faces?
In the pictures above, we're not
counting faces that are 'on the table'. I've coloured the cubes
(according to how many faces are showing) to make the counting a
It would probably be good to make
one of these shapes and do your own counting.
Can you arrange some cubes so that
$28$ of their faces are visible?
You might want to try another way
with a new shape resting on a glass table (you could just pretend!)
so you can count the faces underneath too. Here are two
Cubes that click together might make
So this is your challenge: make a shape that has
$28$ little square faces visible.
Now try on a pretend glass
table and see how many you can make then.
You may like to take photos of them.
Please send in any thoughts, ideas or pictures relating to