We had a good number of solutions sent in to this task.
Emily, Evie, Lily, Chloe and Carys did not say the name of their school but here is what they wrote:

We realised that '2' is the easiest starter number because that is the only one-digit number. Once you have found one which you think is a '2' you can use this to then find the number '25'.
From this, you know what the '5' would look like so then you can find '58'.
After you have found the number '8', you can now find '83'.
This shows you what the number '3' looks like so you can now find '13'.
Finally, now you know what the number '1' looks like so you can find '100'.
You then repeat the same steps for the rest of the different scripts.

Andrea and Emily from Nexus International School in Malaysia got in touch with us.  This is what Andrea wrote and below that is Emily's picture:

Look at the numbers that you know. One number will be in another number, and they all join together! Also, the 100's will have two of the same number. In most of the languages, there will be two dots or two zeros. From that, you will find 13, 83, and 58. Like this you will not need the 25 and 2 but if you need to, find it using what you already know. In five minutes time, all five languages will be cracked!

Gwendolyn from Sha Tin College in Hong Kong explains her approach and she sheds some light on the Chinese system:

The first thing I did was to separate the numbers into groups according to the language they are written in. I call the different languages A, B, C etc.

Now, language A is the number system we usually use, and language B is Chinese, which I also know, so this is 51 written in these languages:

In Chinese, usually two-digit numbers have three characters because the number in the middle is ten. For example, in the number for 25 (see the table above), the two horizontal lines equal 2, the cross is 10 and the final symbol is 5. Basically, it's 2 times 10 + 5.

But before we move on, this is how I grouped the numbers together, e.g. with language C:

It's the same with all the different languages.
So, how did I work it out? This is how I did it:
First I noticed that in every single language, 2 is represented by only one symbol.
Once I knew that, I worked out 25.
Then 58, 83, 13 and 100.

At the end of the time for these to be "live" we had 17 good responses from Moorfield School in the UK.
Thank  you all for the solutions you sent in, do have a look at the new activities that are live now.