Copyright © University of Cambridge. All rights reserved. A
number in a little box is put into a wonderful big box that adds
something to the number and then a new number comes out at the
end: The first time this happens, 10 is put into the little box,
so what happened in the big box to get the answer in the picture
above? Now three more boxes with new numbers in, go into the
wonderful box one at a time. It still does the same as before.
So, what were the three new numbers that went in? Remember that
the wonderful big box did the same for all four numbers that
went in. Imagine four new boxes now (with new numbers in) and
the wonderful box does a new and different add or take away this
time. For one of these boxes the number 10 was put in. The
numbers that come out are these: What could have happened? How
did you work these out? Discuss with others and see if there
were different ways that you found the answers.