Signed Numbers and the Order of Operations
Add, subtract, multiply and divide positive and negative numbers with a few sign rules, work out long expressions in the agreed order (PEMDAS), and estimate to eliminate wrong choices.
What it is
Signed numbers (also called integers when they are whole numbers) are numbers with a + or − sign. Positive numbers are above zero, like money you have. Negative numbers are below zero, like a debt or a temperature below freezing. Zero is neither positive nor negative.
The order of operations is the agreed order for working out an expression with several operations, so that everyone gets the same answer. Many Filipino learners remember it as PEMDAS (some say GEMDAS, with G for grouping symbols).
Why it matters on the exam
The exam has computation items with negatives, powers and brackets mixed together. The wrong choices are built from the usual slips: a lost minus sign, multiplying before dividing, or squaring a negative wrongly. Each slip gives a different wrong answer, and that answer is waiting among the choices.
Signed numbers also appear in everyday work: temperature changes, gains and losses, and balances that go below zero. Estimation saves time on long computations.
- −11
- −1
- 1
- 19
The rest of this lesson, and every other lesson, is part of ReviewTayo.
Read moreIn the full lesson
- How to recognize it on the test
- What to look for (5 checks)
- All 7 rules and tools
- 4 worked examples, every step explained
- 6 common mistakes and how to fix them
- 3 exam techniques
- Remember: 6 key points
- Practice questions with explanations, and your progress saved
More Numerical Ability lessons
ReviewTayo has 51 lessons that follow the official scope of the exam, each with rules, worked examples, common mistakes and practice. Open one and read the first part.