Addition 111
Th is strategy makes it easy to keep track of your calculation and
hold the numbers in your head.
Order of addition
Let’s say we have to add the following numbers:
6
8
- 4
Th e easy way to add the numbers would be to add:
6 + 4 = 10, plus 8 = 18
Most people would fi nd that easier than 6 + 8 + 4 = 18.
So, an easy rule is, when adding a column of numbers, add pairs of
digits to make tens fi rst if you can, and then add the other digits.
You can also add a digit to make up the next multiple of 10. Th at
is, if you have reached, say, 27 in your addition, and the next two
numbers to add are 8 and 3, add the 3 before the 8 to make 30, and
then add 8 to make 38. Using our methods of multiplication will
help you to remember the combinations of numbers that add to 10,
and this should become automatic.
Th is also applies if you had to solve a problem such as 26 + 32 + 14.
We can see that the units digits from 26 and 14 (6 and 4) add to 10,
so it is easy to add 26 and 14. I would add 26 plus 10 to make 36,
plus 4 makes 40, and then add the 32 for an answer of 72. Th is is
an easy calculation compared with adding the numbers in the order
they are written.
BREAKDOWN OF NUMBERS
You also need to know how numbers are made up. Twelve is not
only 10 plus 2 but also 8 plus 4, 6 plus 6, 7 plus 5, 9 plus 3 and 11