I noticed that it was easy because it was just taking one away from the thousands column.
The easiest was Istanbul because everyone can do 2-1.
I recognised Lauceston was the hardest because it isnt just taking one away from the first column it is taking away from the second.
Here are some examples of similar questions i came up with:
If i was travelling to Lauceston and someone took me 10,000km how many km would there be left with?
If i was traveling to Istanbul and somebody took me 2,000kmhow many would i have left?
We also thought if someone had taken us 100km away you take away one from the hundreds column.
Gothenburg was the hardest because you have to remember to go into the thousands column.
If we were adding 1000km on, we had to add one on to the thousands column.