(a)List factors of each, or use repeated division: 36=2²×3², 48=2⁴×3. HCF takes the lowest power of each common factor.

(b)LCM takes the highest power of every prime factor present in either number.

(a)Divide repeatedly by the smallest prime that fits: 72÷2=36, 36÷2=18, 18÷2=9, 9÷3=3, 3÷3=1.

(a)List every number that divides exactly into 24.

(b)A prime number has exactly two factors: 1 and itself.

(a)HCF: 60=2²×3×5, 84=2²×3×7, common factors 2²×3=12. LCM = (60×84)/HCF.

(a)Divide repeatedly by the smallest prime that fits.

(a)Test division by small primes: 91 ÷ 7 = 13 exactly.

(a)Take the highest power of each prime present: 8=2³, 12=2²×3, 20=2²×5.

(a)Multiply 7 by 1, 2, 3, 4, 5.

(a)An even number is exactly divisible by 2. 0 ÷ 2 = 0 exactly.

(a)Order from smallest (most negative) to largest.