Natural and Integral Numbers
Form 2 extends earlier work with natural and integral numbers by applying number-line methods and sign rules to calculations.
Sets and number lines
N = {0,1,2,…} contains whole counting values. Z = {…,−2,−1,0,1,2,…} also contains negative whole values. A number line orders values from left to right; values farther right are greater.
Operations
- For addition and subtraction, use direction and distance on a signed number line.
- For multiplication and division, multiply magnitudes and apply the sign rule: like signs positive, unlike signs negative.
- Check whether the result belongs to N or Z before stating membership.
Worked examples and practice
- −7 + 12 = 5 and 4 − 13 = −9.
- (−9) × 5 = −45 and (−48) ÷ (−6) = 8.
- Classify −3, 0, 2.5 and 14 as members or non-members of N and Z.
