Start with 1 times the number, then try 2, 3, 4 and so on, writing each pair that works. Stop when the pairs start to repeat. Only two factors means prime.
factora number that divides another evenly
multiplea number times 1, 2, 3 and so on
primea number with exactly two factors
compositea number with more than two factors
Watch for: Leaving 1 or the number itself out of the list of factors. Calling 1 prime: it has only one factor. Calling every odd number prime: 9, 15 and 21 are composite.
At home: Arrange 12 coins or buttons into as many different rectangles as you can: 1 by 12, 2 by 6, 3 by 4. Each rectangle is a factor pair.
Sample sheet and answer key
Luna's Space Adventure
Grade 4 · Factors and primes · 4.OA.B.4
NameDate
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
List the factors
Every number that divides it evenly.
Factors of 16:
Factors of 45:
Factors of 30:
Factors of 18:
Prime or composite?
A prime has exactly two factors.
37primecomposite
99primecomposite
78primecomposite
3primecomposite
23primecomposite
91primecomposite
31primecomposite
56primecomposite
Multiples
List the first five multiples.
Multiples of 5:
Multiples of 3:
Sheet
Luna's Space Adventure
Grade 4 · Factors and primes · 4.OA.B.4
Answer key
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
List the factors
Every number that divides it evenly.
Factors of 16:1, 2, 4, 8, 16
Factors of 45:1, 3, 5, 9, 15, 45
Factors of 30:1, 2, 3, 5, 6, 10, 15, 30
Factors of 18:1, 2, 3, 6, 9, 18
Prime or composite?
A prime has exactly two factors.
37primecomposite
99primecomposite
78primecomposite
3primecomposite
23primecomposite
91primecomposite
31primecomposite
56primecomposite
Multiples
List the first five multiples.
Multiples of 5:5, 10, 15, 20, 25
Multiples of 3:3, 6, 9, 12, 15
Answer key
New problems every time, three levels (gentle, core and stretch), themes to pick from, a second page if you want one. Each sheet comes with an answer key and a one-page guide for grown-ups.
