Question 27
Find the prime factorisations of the following numbers: 64, 104, 105, 243, 320, 141, 1728, 729, 1024, 1331, 1000.
We will break down each number into a multiplication of only prime numbers.
Step 1 — Prime factors of 64
Let us start with the number 64. We divide 64 by the smallest prime number, which is 2. We keep dividing the result by 2 until we cannot anymore. We stop when the result is 1.
So, 64 is a multiplication of these prime numbers.

Step 2 — Prime factors of 104
Now let us find factors for 104. We divide 104 by the smallest prime number, 2. We keep dividing by 2 until we cannot anymore. Then we try the next prime number.
The number 13 is a prime number. We divide 13 by 13.
So, 104 is a multiplication of these prime numbers.

Step 3 — Prime factors of 105
Let us find factors for 105. 105 cannot be divided by 2. We check if 105 can be divided by 3. The sum of digits . Since 6 can be divided by 3, 105 can be divided by 3.
35 cannot be divided by 3. We check if 35 can be divided by 5. Since 35 ends in 5, it can be divided by 5.
The number 7 is a prime number. We divide 7 by 7.
So, 105 is a multiplication of these prime numbers.

Step 4 — Prime factors of 243
Let us find factors for 243. 243 cannot be divided by 2. We check if 243 can be divided by 3. The sum of digits . Since 9 can be divided by 3, 243 can be divided by 3.
So, 243 is a multiplication of these prime numbers.

Step 5 — Prime factors of 320
Let us find factors for 320. We divide 320 by the smallest prime number, 2. We keep dividing by 2 until we cannot anymore.
The number 5 is a prime number. We divide 5 by 5.
So, 320 is a multiplication of these prime numbers.

Step 6 — Prime factors of 141
Let us find factors for 141. 141 cannot be divided by 2. We check if 141 can be divided by 3. The sum of digits . Since 6 can be divided by 3, 141 can be divided by 3.
The number 47 is a prime number. We divide 47 by 47.
So, 141 is a multiplication of these prime numbers.

Step 7 — Prime factors of 1728
Let us find factors for 1728. We divide 1728 by the smallest prime number, 2. We keep dividing by 2 until we cannot anymore.
27 cannot be divided by 2. We check if 27 can be divided by 3. The sum of digits . Since 9 can be divided by 3, 27 can be divided by 3.
So, 1728 is a multiplication of these prime numbers.

Step 8 — Prime factors of 729
Let us find factors for 729. 729 cannot be divided by 2. We check if 729 can be divided by 3. The sum of digits . Since 18 can be divided by 3, 729 can be divided by 3.
So, 729 is a multiplication of these prime numbers.

Step 9 — Prime factors of 1024
Let us find factors for 1024. We divide 1024 by the smallest prime number, 2. We keep dividing by 2 until we cannot anymore.
So, 1024 is a multiplication of these prime numbers.

Step 10 — Prime factors of 1331
Let us find factors for 1331. 1331 cannot be divided by 2, 3, 5, or 7. We check if 1331 can be divided by 11.
So, 1331 is a multiplication of these prime numbers.

Step 11 — Prime factors of 1000
Let us find factors for 1000. We divide 1000 by the smallest prime number, 2. We keep dividing by 2 until we cannot anymore.
125 cannot be divided by 2 or 3. We check if 125 can be divided by 5. Since 125 ends in 5, it can be divided by 5.
So, 1000 is a multiplication of these prime numbers.

Answer
(i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x) (xi)
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