Factors, Multiples, and Divisibility
Find number patterns faster, recognize what divides evenly, and know when to use factors, multiples, GCF, or LCM.
Factors, Multiples, and Divisibility
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Factors go in. Multiples come out.
4 and 6 are factors of 24. They divide 24 evenly.
24 is a multiple of 4 and 6.
Factors are numbers that can fit evenly into a number.
Multiples are answers you get when you keep multiplying.
1, 2, 3, 4, 6, 12
12, 24, 36, 48, 60...
Know what the question is asking
- “Divides evenly?” Think factor or divisibility.
- “What comes next?” Think multiples.
- “Greatest number that divides both?” Think GCF.
- “First number both can reach?” Think LCM.
2 → last digit is even
3 → digit sum is divisible by 3
5 → ends in 0 or 5
9 → digit sum is divisible by 9
10 → ends in 0
Six patterns you should recognize
1. Is it a factor?
Is 6 a factor of 42?
42 ÷ 6 = 72. Is it a multiple?
Is 45 a multiple of 9?
9 × 5 = 453. Divisible by 3
Is 7,245 divisible by 3?
7 + 2 + 4 + 5 = 184. Prime or composite?
Is 29 prime?
The only factors are 1 and 29.
5. Greatest common factor
Find the GCF of 18 and 24.
Factors of 18: 1, 2, 3, 6, 9, 18
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
6. Least common multiple
Find the LCM of 4 and 6.
Multiples of 4: 4, 8, 12, 16...
Multiples of 6: 6, 12, 18...
Do we need GCF or LCM?
Two lights blink every 6 seconds and every 8 seconds. If they blink together now, after how many seconds will they blink together again?
- We need a number that both 6 and 8 can reach.
- That means we need a common multiple.
- We want the first one, so we need the least common multiple.
Multiples of 8: 8, 16, 24...
Answer: 24 seconds.
Watch out for these
Factors are limited. Multiples keep going.
That usually needs GCF.
Prime numbers have exactly two factors. The number 1 has only one.
Check the digits first.
Build the skill
These mix factors, multiples, divisibility, prime numbers, GCF, and LCM.
Can you spot it fast?
Five short questions. Use the fastest valid method.
Can you do it without hints?
Score 5/5 to verify this competency. If you miss one, a fresh set will be ready.
Not sure whether a problem needs GCF or LCM?
Send Teacher Abi the question that confused you and your result. I can help you spot the clue faster.
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