Parentheses

Parentheses are made like this ( ).

They show what part we wish to work first in a number sentence. Some people call then brackets.

4 + 3 + 2 = 9

We can think of this as 7 + 2 = 9 or 4 + 5 = 9

If we use parentheses in this way

(4 + 3) + 2 becomes 7 + 2 = 9

4 + (3 + 2) becomes 4 + 5 = 9

Thus, to add we may group these numbers in any order.

Examples using parentheses:

(i) 1 + 4 + 5 = 10

We can think of this as 5 + 5 = 10 or 1 + 9 = 10

If we use parentheses in this way

(1 + 4) + 5 becomes 5 + 5 = 10

1 + (4 + 5) becomes 1 + 9 = 10

Thus, to add we may group these numbers in any order.

(ii) In the number sentence 2 + 1 + 1 + 5 = 9 first make 4s by using parentheses and then add.

Thus, to make 4s we may group these numbers in the order (2 + 1 + 1) + 5 and then add 4 + 5 = 9.

(iii) In the number sentence 2 + 5 + 1 = 8 first make 6s by using parentheses and then add.

Thus, to make 6s we may group these numbers in the order 2 + (5 + 1) and then add 2 + 6 = 8.

2nd Grade Math Practice

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