-
Signs, "[" and "]", used to indicate that the operation(s) on the quantities enclosed should be worked out first or should be treated as a unit. Brackets are normally used after parentheses are used.
For example,
2 × [(6 - 4) × 3 + 1] - 1
= 2 × [2 × 3 + 1] - 1
= 2 × [6 + 1] - 1
= 2 × 7 - 1
= 13.
