6.7 Small Group · Group 2
Second Challenge Form · Non-Routine Extension · Same Standard, New Problems
Find Factors and Multiples · Factor · Procedural Fluency · Real-World Applications
- You already can do this. So we go up a level, not up a number: find what is always true, show it a second way, and be ready to defend it with a reason instead of an answer.
- The store has 48 pencils and 36 notebooks. Every combo pack must hold the same number of each, with nothing left over — so the number of packs has to be a factor of BOTH quantities.
- Factors of 48: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48. Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36. Listing them in order is what makes the comparison easy.
- The numbers in both lists are the common factors: 1, 2, 3, 4, 6, and 12.
- The greatest of those is 12, so the GCF of 48 and 36 is 12. The manager can make 12 combo packs — each holding 48 ÷ 12 = 4 pencils and 36 ÷ 12 = 3 notebooks.
- A factor tree breaks each number into primes. 48 = 2 × 2 × 2 × 2 × 3, and 36 = 2 × 2 × 3 × 3.
- Now look at what the two share: two 2s and one 3.
- Multiply the shared primes: 2 × 2 × 3 = 12.
- Same answer as the lists, 12 — which is the check. For big numbers, the factor tree is usually the faster road.
- Now prove it: say why that move had to work at all — not just that it did.
- Sentence frame — convince a skeptic: "My method works because ___ . It would stop working if ___ ."
- Find Factors and Multiples (Hallar factores y múltiplos) — Listing what divides a number evenly (its factors) and what it divides into evenly (its multiples), then finding what two numbers share.
- Factor (Factor) — A whole number that divides another number evenly, with no remainder.
- Multiple (Múltiplo) — The result of multiplying a number by 1, 2, 3, and so on — where you land when you skip-count by it.
- Greatest common factor (GCF) (Máximo común divisor (MCD)) — The largest number that is a factor of two or more numbers. It answers “how many equal groups can I make?”
- Least common multiple (LCM) (Mínimo común múltiplo (mcm)) — The smallest number that is a multiple of two or more numbers. It answers “when will these line up again?”
- Factor pair (Par de factores) — Two factors that multiply to make a number. In a word problem, one is the number of groups and the other is the size of each group.
- A common mistake is reaching for the wrong tool: listing FACTORS for a problem about repeating cycles. Ayasha's classes repeat every 6 and 8 weeks, so the weeks they land on are multiples — answering with the GCF of 2 claims a class that meets every 8 weeks happens in week 2. Use the size of the answer as a check: a GCF is never larger than the smaller number, and an LCM is never smaller than the larger one.
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1 MULTIPLE CHOICE
Asking for the LCM of 4 and 6, Kai lists multiples until they match: 4, 8, 12 and 6, 12. Nia multiplies 4 × 6 = 24. Whose method gives the least common multiple?
- AKai — 12 is the first shared multiple; Nia's 24 is a common multiple but not the least
- BNia — multiplying the two numbers always gives the LCM
- CBoth — 12 and 24 are equally correct answers
- DNeither — the LCM of 4 and 6 is 2
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
What is the least common multiple of 4 and 6?
- A12
- B24
- C2
- D10
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
Using prime factors, 48 = 2 × 2 × 2 × 2 × 3 and 36 = 2 × 2 × 3 × 3. What is their GCF?
- A12, from the shared 2 × 2 × 3
- B144, from multiplying all the primes
- C6, from one 2 and one 3
- D2, the only prime they share
✏️ Workspace & Solution Steps -
4 MULTIPLE CHOICE
Ayasha has painting every 8 weeks and pottery every 6 weeks, both this week. When do they next fall in the same week?
- AIn 24 weeks
- BIn 48 weeks
- CIn 14 weeks
- DIn 2 weeks
✏️ Workspace & Solution Steps
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5 ERROR ANALYSIS
Fix our table's thinking
- 1The problem:Ayasha has painting every 8 weeks and pottery every 6 weeks, both this week. When do they next fall in the same week?
- 2A classmate at our table answered:In 48 weeks
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation -
6 ERROR ANALYSIS
Find the error
- 1Problem:Ayasha has painting every 8 weeks and pottery every 6 weeks. When do both fall in the same week?
- 2Step 1:Factors of 8: 1, 2, 4, 8
- 3Step 2:Factors of 6: 1, 2, 3, 6
- 4Step 3:The greatest common factor is 2, so both classes meet in week 2.
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation
Writing Task: Justify why your mathematical solution is accurate and complete.