This week’s puzzle was given to us by a maths teacher who used to set it as a revision exercise.

The problem is to make a series of equations containing four fours and any number of common mathematical symbols. The first equation must total one, the second equation must total two, and so on . . . as far as you can go. The teacher said that the one pupil produced equations from one all the way to 32 in one hour. As you’ve got as much time as you want, how far can you extend the sequence.

In this puzzle you can combines fours to make 44 (or 444 or 4,444) so 44 + 44 = 88 is a valid equation. And you can raise to the power of 4, so 4 ^ 4 + 4 + 4 = 264 is also valid. You must use four fours each time - you can't use three!

We asked how long a sequence of equations you could produce - here is a list to 50, some from us and some from our solvers:

NB We've added some brackets that aren't really necessary (if you are familiar with BODMAS), but they make things clearer.

$$ 44 / 44 = 1 $$

$$ (4 / 4) + (4 / 4) = 2 $$

$$ (4 + 4 + 4) / 4 = 3 $$

$$ 4 - 4 + \sqrt{4} + \sqrt{4} = 4 $$

$$ (4! / 4) - (4 / 4) = 5 $$

$$ (4! / 4) + 4 - 4 = 6 $$

$$ (44 / 4) - 4 = 7 $$

$$ 4 + 4 + 4 - 4 = 8 $$

$$ (4 + 4) + (4 / 4) = 9 $$

$$ 44 / 4.4 = 10 $$

$$ (4 / .4) + (4 / 4) = 11 $$

$$ 4 + 4 + \sqrt{4} + \sqrt{4} = 12 $$

$$ (44 / 4) + \sqrt{4} = 13 $$

$$ 4 + 4 + 4 + \sqrt{4} = 14 $$

$$ (4 * 4) - (4 / 4) = 15 $$

$$ 4 + 4 + 4 + 4 = 16 $$

$$ (4 * 4) + (4 / 4) = 17 $$

$$ (4 * 4) + 4 - \sqrt{4} = 18 $$

$$ 4! - (4 / 4) - 4 = 19 $$

$$ 4! - 4 + 4 - 4 = 20 $$

$$ 4! - 4 + (4 / 4) = 21 $$

$$ 4! - 4 + 4 - \sqrt{4} = 22 $$

$$ 4! - \sqrt{4} + (4 / 4) = 23 $$

$$ 4! + (4 ^ (4 - 4)) = 24 $$

$$ 4! - (4 / 4) + \sqrt{4} = 25 $$

$$ 4! + 4 - 4 + \sqrt{4} = 26 $$

$$ 4! + 4 - (4 / 4) = 27 $$

$$ 4! + 4 - 4 + 4 = 28 $$

$$ 4! + 4 + (4 / 4) = 29 $$

$$ 4! + \sqrt{4} + \sqrt{4} + \sqrt{4} = 30 $$

$$ (4! + 4) / 4 + 4! = 31 $$

$$ (4 * 4) + (4 * 4) = 32 $$

$$ (\sqrt{4} / .4) + 4 + 4! = 33 $$

$$ 4! + (4! / 4) + 4 =34 $$

$$ 4! + ((4! - \sqrt{4}) / \sqrt{4}) = 35 $$

$$ 4! + ((4! / 4) * \sqrt{4}) = 36 $$

$$ 4! + ((4! + \sqrt{4}) / \sqrt{4}) = 37 $$

$$ 44 - (4! / 4) = 38 $$

$$ 44 - (\sqrt{4} / .4) = 39 $$

$$ 44 - (\sqrt{4} * \sqrt{4}) = 40 $$

$$ 44 - \sqrt{(4 / .4)} (recurring - can't do the dot over the four) = 41 $$

$$ 44 - 4 + \sqrt{4} = 42 $$

$$ 44 - (4 / 4) = 43 $$

$$ 44 + 4 - 4 = 44 $$

$$ 44 + (4 / 4) = 45 $$

$$ 44 + 4 - \sqrt{4} = 46 $$

$$ 44 + \sqrt{(4 / .4)} (recurring - can't do the dot over the four) = 47 $$

$$ 44 + \sqrt{4} + \sqrt{4} = 48 $$

$$ 44 + (\sqrt{4} / .4) = 49 $$

$$ 44 + 4 + \sqrt{4} = 50 $$