Multiplication and Division To Make A Perfect Cube
Smallest number multiplication to make perfect cube:
Suppose a number is given, we first have to find its prime factorization. Then, we have to make a pair of three similar numbers. If the number is not a perfect cube, then any one or two numbers will be remaining. We have to multiply those numbers with the same number to make the number a perfect cube.
For example: if the number is 243
Step 1: we need to find the prime factorization of 243
3 243
3 81
3 27
3 9
3 3
1
Step 2: Making pair of prime factorisation of number 243
243 = 3 * 3 * 3 * 3 * 3
————
= 3^3 * 3^2
This is not a perfect cube. Next, now we will make the number a perfect cube
Step 3: To make the number 243 a perfect cube, the missing numeral is three. So we will multiply 3 to the number 243 to make it a perfect cube.
Step 4: So the perfect cube number is 243 * 3= 729
Smallest number division to make perfect cube:
Suppose a number is given, we first have to find its prime factorization. Then, we have to make a pair of three similar numbers (since we are dealing with a cube of numbers). If the number is not a perfect cube, then any one or two numbers will be remaining. We have to divtopicIde those numbers with the same number to eliminate them so that the remaining numbers form a perfect cube.
For example: If the number is 675
Step 1: first we have to find the prime factorization for 675
3 675
3 225
3 75
5 25
5 5
1
Step 2: Making pair of prime factorisation of number 675
675 = 3 * 3 * 3 * 5 * 5
————
= 3^3 *5^2.
This is not a perfect cube. So, how can we make the number a perfect cube?
Step 3: To make the number 675 a perfect cube, Here the number 5 is repeated two times instead of three times. So 5* 5 =2 5
So, we will divtopicIde 25 from the number 675 and get the perfect cube.
Step 4: 675 / 25 = 27
So the perfect cube number will be 27.
Mixed Bag Sums:
Example 1: Is 6655 a perfect cube? If not, find the smallest natural number by which 6655 must be multiplied so that the product is a perfect cube?
Solution:
Prime factorisation of 6655
5 6655
11 1331
11 121
11 11
1
6655= 5 * 11 * 11 * 11
—————-
= 5^1 * 11^3
The number 6655 is not a perfect square.
As the number five is present only once, we need to multiply 5 with 5. Hence, we get 5 * 5 = 25.
So, we need to multiply 25 with 6655 to make it a perfect cube.
6655 * 25 = 166375
Example 2: Find the smallest number which should be divtopicIded by 23625 to make it a perfect cube.
Solution: Initially, we have to find the prime factorization of 23625
3 23625
3 7875
3 2625
5 875
5 175
5 35
7 7
1
23625= 3 * 3 * 3 * 5 * 5 * 5 * 7
= ———— ————
The number 23625 is not a perfect cube. In prime factorization of 23625, there are pairs of the numbers three and five. Only, the number 7 is left out. So, we will divtopicIde seven from the number to 23625.
So 23625 /7 = 3375
So the number 3375 is a perfect cube.