Place four pebbles on the sand in the form of a square. Keep adding
as few pebbles as necessary to double the area. How many extra
pebbles are added each time?
Suppose we allow ourselves to use three numbers less than 10 and
multiply them together. How many different products can you find?
How do you know you've got them all?
Investigate the different shaped bracelets you could make from 18
different spherical beads. How do they compare if you use 24 beads?
Now, I wonder what Becky changed her search to? If Becky is
going to change her search to try and arrive at an answer perhaps
she wants to think about this idea.
her family from Leicester, England worked on this Vuvvian problem.
Alex explains how they set about arriving at a solution:
Now although 210 years is a long time, Anita and Jing Jing from
Kilvington Girls' Grammar in Australia, think that's only the half
of it...in fact, they think that it is 420 year wait between
Super-eclipses. But Thomas, from Suffolk, thinks it's way longer
than that - twice as long.
He wrote: "There are 840 Vuvvianyears between the Super
Eclipses. I worked it out by going through the 7 times table and
writing it down seeing that this would be the hardest to divide by.
I then realised that the number had to end in a zero because it had
to be divisible by 5 and 2. That meant that all I had to do was
find out if the multiples of 7 were divisible by 3, 4 and 6 and if
they were multiply them by 10. In the end 84 was the lowest number
divisible by 3, 4 and 6 so I multiplied it by 10 and got 840."
Franco and Jonny from Northamptonshire agree that is it
420. They say:
We started off with 42. Every number goes into 42, except 5, so
we multiplied it by 5.
6 doesn't go into 210, so we went back to 42. We then multiplied
42 by 10, to get 420. We checked by dividing 420 by 1, 2, 3, 4, 5,
6 and 7. They are all factors of 420. So the overall answer is 420.
So, who is correct?