Taking practice question 2, you get 16 for the total of the left-hand column – remember that.
For the next column you find a total of 18, so the 1 in this 18 is taken over to the 16 in the first column, and you get 178 with the 8 appended. Remember 178.
Finally, the right-hand column totals 26, so carry the 2 onto the 178 (to make it 180) and append the 6 to give 1806.
I hope this explains it. But there is another method which we will come to later which will allow you to write the digits down one after the other rather than hold the whole thing mentally, which can be a challenge if there are many figures involved.