Question

numbers
a prime number is a whole number that has exactly two different factors—1 and the number itself. a composite number is a whole number that has more than two different factors.
for each number:

• list all of its factors.
• write whether the number is prime or composite.
• circle all of the factors that are prime numbers.

number factors prime or composite?
① 11 1,11 prime
② 19 1,19 prime
③ 24 1,2,4,2,12,4,6 composite
④ 29 1,29 prime
⑤ 36 1,36,6,6,4,9,3,12
⑥ 49
⑦ 50
⑧ 70
⑨ 100

practice
solve.
⑩ 841 + 527 =
⑪ = 3,263 + 5,059
⑫ 7,461 + 2,398 =
⑬ = 4,172 - 3,236
⑭ 8,158 = 5,071 +
⑮ 3,742 - 3,349 =

Explanation:

Step1: Find factors of 36

We start from 1 and check which numbers divide 36 evenly. $1\times36 = 36$, $2\times18=36$, $3\times12 = 36$, $4\times9=36$, $6\times6 = 36$. So the factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36.

Step2: Determine if 36 is prime or composite

Since 36 has more than two factors (1, 2, 3, 4, 6, 9, 12, 18, 36), it is a composite number.

Step3: Find factors of 49

$1\times49=49$ and $7\times7 = 49$. So the factors of 49 are 1, 7, 49.

Step4: Determine if 49 is prime or composite

Since 49 has more than two factors (1, 7, 49), it is a composite number.

Step5: Find factors of 50

$1\times50 = 50$, $2\times25=50$, $5\times10 = 50$. So the factors of 50 are 1, 2, 5, 10, 25, 50.

Step6: Determine if 50 is prime or composite

Since 50 has more than two factors (1, 2, 5, 10, 25, 50), it is a composite number.

Step7: Find factors of 70

$1\times70=70$, $2\times35 = 70$, $5\times14=70$, $7\times10 = 70$. So the factors of 70 are 1, 2, 5, 7, 10, 14, 35, 70.

Step8: Determine if 70 is prime or composite

Since 70 has more than two factors (1, 2, 5, 7, 10, 14, 35, 70), it is a composite number.

Step9: Find factors of 100

$1\times100 = 100$, $2\times50=100$, $4\times25 = 100$, $5\times20=100$, $10\times10 = 100$. So the factors of 100 are 1, 2, 4, 5, 10, 20, 25, 50, 100.

Step10: Determine if 100 is prime or composite

Since 100 has more than two factors (1, 2, 4, 5, 10, 20, 25, 50, 100), it is a composite number.

Step11: Solve 841+527

$841+527=(800 + 41)+(500+27)=(800 + 500)+(41+27)=1300 + 68=1368$.

Step12: Solve 7461+2398

$7461+2398=(7000+400 + 60+1)+(2000+300+90 + 8)=(7000+2000)+(400+300)+(60 + 90)+(1+8)=9000+700+150+9=9859$.

Step13: Solve 3263+5059

$3263+5059=(3000+200+60 + 3)+(5000+50+9)=(3000+5000)+(200)+(60+50)+(3 + 9)=8000+200+110+12=8322$.

Step14: Solve 4172 - 3236

$4172-3236=(4000+100+70+2)-(3000+200+30+6)= (4000-3000)+(100 - 200)+(70-30)+(2 - 6)=1000-100 + 40-4=936$.

Step15: Solve 3742-3349

$3742-3349=(3000+700+40+2)-(3000+300+40+9)=(3000-3000)+(700-300)+(40-40)+(2 - 9)=400-7=393$.

Answer:

Number	Factors	Prime or Composite?
49	1, 7, 49	Composite
50	1, 2, 5, 10, 25, 50	Composite
70	1, 2, 5, 7, 10, 14, 35, 70	Composite
100	1, 2, 4, 5, 10, 20, 25, 50, 100	Composite
10	1368
11	8322
12	9859
13	936
14	3087	(since $8158-5071 = 3087$)
15	393