Lesson 2 of 16Article18 minFREE
The Four Operations with Confidence
Adding a positive number moves right on the number line; subtracting a positive number moves left. Adding a negative is the same as subtracting its absolute value.
01Addition and subtraction as movement
Adding a positive number moves right on the number line; subtracting a positive number moves left. Adding a negative is the same as subtracting its absolute value.
02Multiplication and division
Multiplication is repeated addition; division asks how many equal groups fit. Sign rules are identical for both: same signs → positive result; different signs → negative result.
- Positive × positive = positive; negative × negative = positive.
- Positive × negative = negative.
- Division by zero is undefined — there is no number that multiplies by 0 to give a non-zero result.
- Order of operations: parentheses, exponents, multiply/divide left-to-right, add/subtract left-to-right (PEMDAS/BODMAS).
03Worked example
Evaluate 12 − 3 × (2 + (−4))².
Inside parentheses: 2 + (−4) = −2. Square: (−2)² = 4. Multiply: 3 × 4 = 12. Subtract: 12 − 12 = 0.