We have been working systematically to solve a  maths problems using our knowledge of multiplication and division.

The problem was:

In the forest there is a Deca Tree. A Deca Tree has 10 trunks, and on each trunk there are 10 branches, and on each branch there are 10 twigs, and on each twig there are 10 leaves. One day a woodcutter came along and cut down one trunk from the tree.
Then he cut off one branch from another trunk of the tree.
Then he cut off one twig from another branch.
Finally he pulled one leaf from another twig.

How many leaves were left on the tree then?

There are 10 leaves per twig
There are 10 twigs per branch
10 leaves x 10 twigs = 100 leaves per branch
There are 10 branches per trunk
100 leaves x 10 branches = 1000 leaves per trunk
There are 10 trunks per tree
1000 leaves x 10 trunks = 10 000 leaves on the tree

Cut off one trunk: 10 000 – 1000 = 9000 leaves left
Cut off one branch: 9000 – 100 = 8900 leaves left
Cut off one twig: 8900 – 10 = 8890 leaves left
Pull off one leaf: 8890 – 1 = 8889 leaves left

There are 8889 leaves left on the tree.