Math / Numbers & Operations

QuestionSparx Maths New! Multi Part Question - when you answer this question we'll mark each part individually Bookwork code: 1B Calculator not allowed
For each number, decide whether it is prime or not prime: a) 51 b) 87

Studdy Solution

STEP 1

What is this asking? We need to figure out if 51 and 87 are prime numbers. Watch out! Remember a prime number is a whole number greater than 1 that has only two divisors: 1 and itself.
Don't get tricked by numbers that look prime but aren't!

STEP 2

1. Check 51
2. Check 87

STEP 3

Alright, let's tackle 51!
Is it prime?
A prime number is only divisible by 1 and itself.
So, we need to see if 51 has any sneaky divisors other than 1 and 51.

STEP 4

Let's think about divisibility rules.
Is 51 divisible by 2?
Nope, it's not even.
How about 3?
The divisibility rule for 3 is to add up the digits. $5 + 1 = 6$ , and 6 is divisible by 3!

STEP 5

Let's check! $51 \div 3$ .
We know that $3 \cdot 10 = 30$ , and $51 - 30 = 21$ , and $3 \cdot 7 = 21$ .
So, $30 + 21 = 51$ , which means $3 \cdot 10 + 3 \cdot 7 = 51$ , or $3 \cdot (10 + 7) = 51$ , which simplifies to $3 \cdot 17 = 51$ .
Boom!

STEP 6

Since 51 is divisible by 3 and 17, in addition to 1 and itself, it's not a prime number.

STEP 7

Now, let's investigate 87.
Is this number prime?
Let's apply our divisibility rule knowledge again!

STEP 8

Is 87 divisible by 2?
Nah, it's not even.
What about 3?
Let's add the digits: $8 + 7 = 15$ .
Hey, 15 is divisible by 3!

STEP 9

Let's do the division: $87 \div 3$ .
We know that $3 \cdot 20 = 60$ , and $87 - 60 = 27$ , and $3 \cdot 9 = 27$ .
So, $60 + 27 = 87$ , which means $3 \cdot 20 + 3 \cdot 9 = 87$ , or $3 \cdot (20 + 9) = 87$ , which simplifies to $3 \cdot 29 = 87$ .
Awesome!

STEP 10

Since 87 is divisible by 3 and 29, as well as 1 and itself, it's also not a prime number.

STEP 11

a) 51 is not prime. b) 87 is not prime.

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QuestionSparx Maths New! Multi Part Question - when you answer this question we'll mark each part individually Bookwork code: 1B Calculator not allowed
For each number, decide whether it is prime or not prime: a) 51 b) 87

Studdy Solution

STEP 1

What is this asking? We need to figure out if 51 and 87 are prime numbers. Watch out! Remember a prime number is a whole number greater than 1 that has only two divisors: 1 and itself.
Don't get tricked by numbers that look prime but aren't!

STEP 2

1. Check 51
2. Check 87

STEP 3

Alright, let's tackle 51!
Is it prime?
A prime number is only divisible by 1 and itself.
So, we need to see if 51 has any sneaky divisors other than 1 and 51.

STEP 4

Let's think about divisibility rules.
Is 51 divisible by 2?
Nope, it's not even.
How about 3?
The divisibility rule for 3 is to add up the digits. $5 + 1 = 6$ , and 6 is divisible by 3!

STEP 5

Let's check! $51 \div 3$ .
We know that $3 \cdot 10 = 30$ , and $51 - 30 = 21$ , and $3 \cdot 7 = 21$ .
So, $30 + 21 = 51$ , which means $3 \cdot 10 + 3 \cdot 7 = 51$ , or $3 \cdot (10 + 7) = 51$ , which simplifies to $3 \cdot 17 = 51$ .
Boom!

STEP 6

Since 51 is divisible by 3 and 17, in addition to 1 and itself, it's not a prime number.

STEP 7

Now, let's investigate 87.
Is this number prime?
Let's apply our divisibility rule knowledge again!

STEP 8

Is 87 divisible by 2?
Nah, it's not even.
What about 3?
Let's add the digits: $8 + 7 = 15$ .
Hey, 15 is divisible by 3!

STEP 9

Let's do the division: $87 \div 3$ .
We know that $3 \cdot 20 = 60$ , and $87 - 60 = 27$ , and $3 \cdot 9 = 27$ .
So, $60 + 27 = 87$ , which means $3 \cdot 20 + 3 \cdot 9 = 87$ , or $3 \cdot (20 + 9) = 87$ , which simplifies to $3 \cdot 29 = 87$ .
Awesome!

STEP 10

Since 87 is divisible by 3 and 29, as well as 1 and itself, it's also not a prime number.

STEP 11

a) 51 is not prime. b) 87 is not prime.

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QuestionSparx Maths New! Multi Part Question - when you answer this question we'll mark each part individually Bookwork code: 1B Calculator not allowedFor each number, decide whether it is prime or not prime: a) 51 b) 87

Studdy Solution

STEP 1

What is this asking? We need to figure out if 51 and 87 are prime numbers. Watch out! Remember a prime number is a whole number greater than 1 that has only two divisors: 1 and itself.Don't get tricked by numbers that *look* prime but aren't!

STEP 2

1. Check 512. Check 87

STEP 3

Alright, let's **tackle 51**!Is it prime?A prime number is only divisible by 1 and itself.So, we need to see if 51 has any sneaky divisors other than 1 and 51.

STEP 4

Let's **think about divisibility rules**.Is 51 divisible by 2?Nope, it's not even.How about 3?The divisibility rule for 3 is to add up the digits. 5+1=65 + 1 = 65+1=6, and 6 *is* divisible by 3!

STEP 5

STEP 6

Since 51 is divisible by 3 and 17, in addition to 1 and itself, it's **not** a prime number.

STEP 7

Now, let's **investigate 87**.Is *this* number prime?Let's apply our divisibility rule knowledge again!

STEP 8

Is 87 divisible by 2?Nah, it's not even.What about 3?Let's add the digits: 8+7=158 + 7 = 158+7=15.Hey, 15 *is* divisible by 3!

STEP 9

STEP 10

Since 87 is divisible by 3 and 29, as well as 1 and itself, it's **also not** a prime number.

STEP 11

a) 51 is **not prime**. b) 87 is **not prime**.

Get Studdy

Studdy solves anything!

Start learning now

Download Studdy AI Tutor now. Learn with ease and get all help you need to be successful at school.

QuestionSparx Maths New! Multi Part Question - when you answer this question we'll mark each part individually Bookwork code: 1B Calculator not allowed
For each number, decide whether it is prime or not prime: a) 51 b) 87

What is this asking? We need to figure out if 51 and 87 are prime numbers. Watch out! Remember a prime number is a whole number greater than 1 that has only two divisors: 1 and itself.
Don't get tricked by numbers that look prime but aren't!

1. Check 51
2. Check 87

Alright, let's tackle 51!
Is it prime?
A prime number is only divisible by 1 and itself.
So, we need to see if 51 has any sneaky divisors other than 1 and 51.

Let's think about divisibility rules.
Is 51 divisible by 2?
Nope, it's not even.
How about 3?
The divisibility rule for 3 is to add up the digits. $5 + 1 = 6$ , and 6 is divisible by 3!

Since 51 is divisible by 3 and 17, in addition to 1 and itself, it's not a prime number.

Now, let's investigate 87.
Is this number prime?
Let's apply our divisibility rule knowledge again!

Is 87 divisible by 2?
Nah, it's not even.
What about 3?
Let's add the digits: $8 + 7 = 15$ .
Hey, 15 is divisible by 3!

Since 87 is divisible by 3 and 29, as well as 1 and itself, it's also not a prime number.

a) 51 is not prime. b) 87 is not prime.