SUBTRACTION
Subtraction is one of the most basic operations in mathematics and is directly linked to the idea of taking or knowing how much is missing.
Example:
Joãozinho had 4 strollers before giving 1 to his cousin. It is not difficult to see that Joãozinho was left with 3 carts.
The symbol used to represent the subtraction is the (-) . Look:
4 – 1 = 3
In this example we have to:
4 is the MINUENDO
1 is SUBTRAENDO
3 is the DIFFERENCE or REST
THE ALGORITHM
The structure of the subtraction algorithm is as follows:
To use the algorithm, the minuendo and subtrendendo must be positioned from right to left, so that first we subtract the units, then the tens, hundreds, etc.
Comments
- The order of the parcels makes all the difference. The minuendo must always be placed above the subtrend;
- The algorithm can be used to subtract just one minuend from a subtrend;
- The minuendo must be greater than the subtracting.
Example 1. Subtract 65 from 42.
Units: 5 – 2 = 3
Dozens: 6 – 4 = 2
Example 2. Subtract 968 from 151.
Units: 8 – 1 = 7
Dozens: 6 – 5 = 1
Hundreds: 9 – 1 = 8
Example 3. Subtract 846 from 572.
We now have a special case. When we try to subtract the tens, we have to 4> 7. Whenever this occurs, the 4 will “borrow” with the number to its left, changing to 14. The 8 in turn, will become 7.
Units: 6 – 2 = 4
Dozens: 14 – 7 = 7
Hundreds: 7 – 5 = 2
