Addition
History of Marcelo Guedes - Roraima, Brasil
Addition. Properties
30 + 11 = 50 (read: The sum of thirty-nine and eleven is equal to 50.)
39 and 11 are the installments and 50 is the sum.
Addition properties:
- Commutative: a + b = b + a
Changing the order of the installments the sum does not change.
39 + 11 = 11 + 39 = 50
- Associative: (a + b) + c (b + c)
The sum does not change when associating the installments differently.
(39 + 11) + 28 = 39 + (11 + 28) = 78
- Existence of neutral elements : a + 0 = 0 + a = a
o (zero) is the neutral element of addition.
To make an estimate for a sum, we usually round numbers to the nearest tens or hundreds.
39 + 11 + 28 = 78 (Exact value)
40 + 10 + 30 = 80 (Estimate)
30 + 11 = 50 (read: The sum of thirty-nine and eleven is equal to 50.)
39 and 11 are the installments and 50 is the sum.
Addition properties:
- Commutative: a + b = b + a
Changing the order of the installments the sum does not change.
39 + 11 = 11 + 39 = 50
- Associative: (a + b) + c (b + c)
The sum does not change when associating the installments differently.
(39 + 11) + 28 = 39 + (11 + 28) = 78
- Existence of neutral elements : a + 0 = 0 + a = a
o (zero) is the neutral element of addition.
To make an estimate for a sum, we usually round numbers to the nearest tens or hundreds.
39 + 11 + 28 = 78 (Exact value)
40 + 10 + 30 = 80 (Estimate)
