Math Problem Statement
a number N is between 2 to the fifth power and 3 to the fourth power . How many possible values of N are there that has even number of factors?
Solution
We are given that a number lies between and , and we need to determine how many possible values of have an even number of factors.
Step 1: Calculate and
So, the number lies between 32 and 81.
Step 2: Determine the numbers between 32 and 81
The integers between 32 and 81 are: These numbers are from 33 to 80, inclusive, which gives us:
Step 3: Determine when a number has an even number of factors
A number has an even number of factors unless it is a perfect square. This is because the factors of a number usually come in pairs (e.g., for 12, the factors are , , ), but for a perfect square, one factor is repeated (e.g., for 36, the factors are , , , , ).
Step 4: Identify the perfect squares between 32 and 81
We find the perfect squares between 32 and 81: So the perfect squares in this range are 36, 49, 64, and 81.
Step 5: Count the numbers with an even number of factors
The total number of integers between 33 and 80 is 48. Out of these, 4 are perfect squares (36, 49, 64, 81), which have an odd number of factors. The remaining numbers will have an even number of factors:
Final Answer:
There are 44 numbers between 32 and 81 that have an even number of factors.
Would you like further details or have any questions? Here are some related questions:
- How do you calculate the number of factors of a given number?
- What is the significance of perfect squares in factorization?
- Can a number have both an odd and an even number of factors?
- How would the answer change if the range for was extended?
- What is the connection between prime factorization and the number of divisors?
Tip: The number of divisors of a number can be found using its prime factorization!
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Math Problem Analysis
Mathematical Concepts
Number Theory
Factors
Perfect Squares
Formulas
Number of divisors formula: product of (exponents + 1)
Even number of factors unless perfect square
Theorems
Perfect squares have an odd number of factors
Non-perfect squares have even number of factors
Suitable Grade Level
Grades 8-10
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