1.2 Factors

• Divisibility of numbers by 2, 3, 4, 5, 6, 8, 9, 10 and 11
• Composite numbers
• Prime factorisation of composite numbers as a product of primes, including power form
• Greatest Common Divisor (GCD) by factor method
• Least Common Multiple (LCM) by factor method
• GCD and LCM in Kenyan real-life situations

• test divisibility of numbers by 2, 3, 4, 5, 6, 8, 9, 10 and 11 in different situations
• express composite numbers as a product of prime factors in different situations
• work out the Greatest Common Divisor (GCD) and the Least Common Multiples (LCM) of numbers by factor method in different situations
• apply the Greatest Common Divisor (GCD) and the Least Common Multiples (LCM) in real-life situations
• reflect on the use of factors in real-life situations

“Where do we use factors in day-to-day activities?”

“How do we use factors in day-to-day activities?”

“How do we apply the GCD and the LCM in day-to-day activities?”

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1. Divisibility by 2, 5 and 10
   40 min · 1 practice tasks · quiz
   Test 2, 5 and 10 from the last digit, using Kenyan money, eggs and market totals.
2. Divisibility by 3, 6 and 9
   40 min · 1 practice tasks · quiz
   Add the digits to test 3 and 9; combine the 2-test with the 3-test to test 6.
3. Divisibility by 4, 8 and 11
   40 min · 1 practice tasks · quiz
   Use the last two digits for 4, the last three for 8, and the alternating digit sum for 11.
4. Composite numbers and listing factors
   40 min · 1 practice tasks · quiz
   Tell prime from composite by counting factors, and list every factor with a rainbow, using divisibility tests as shortcuts.
5. Prime factorisation
   40 min · 1 practice tasks · quiz
   Break a composite into a product of primes with a factor tree, then write the product in power form.
6. GCD by the factor method
   40 min · 1 practice tasks · quiz
   Find the greatest common divisor from shared prime factors, then use it to share, cut cloth and choose a measuring can.
7. LCM by the factor method, and choosing GCD or LCM
   40 min · 1 practice tasks · quiz
   Find the least common multiple from highest prime powers, use it for packing and meeting times, and choose GCD or LCM from the story.