- Addition in metric measures
As the metric measures are based on powers of ten, addition and subtraction in metric
system is just like addition and subtraction in number system.
Eg. : Add : 6m 3 dm 5 cm ; 5m 4dm 5 cm and 5m 3 dm 2 cm
m dm cm
6 3 5
5 4 5
5 3 2
17 1 2
That is, the result is 17m 1 dm 9 cm
The idea may be explained to the child that the changes in higher values are in terms
of tens and therefore, the additions is just like regular additions.
The concept of borrowing numbers from the higher columns is similar to that of
abacus and therefore use of abacus during this lesson will enhance the learning skills
of the child.
- Subtraction in metric measures
The process of subtraction in metric system is also just similar to addition.
Eg. : Subtract 5 g 4 dg 3 cg from 7 g 5 dg 6 cg
g dg cg
7 5 6
5 4 3
2 1 3
Therefore the difference between the two quantities is 2 g 1 dg 3 cg