A $\textit{palindrome}$ is a positive integer which reads the same forward and backward, like $12321$ or $4884$. How many $4$-di
1 answer:
There are 90 4-digit palindromes
<h3>What are palindromes?</h3>Palindromes are numbers whose reverse is the same as the original number
<h3>How to determine the count of 4-digit palindromes</h3>Since the digit is 4, then
- The first digit of the palindrome can be any of 1 to 9 (i.e. 9 digits)
- The second digit can be any of 0 - 9 (i.e. 10 digits)
- The third digit must be the second digit (i.e. 1 digit)
- The last digit must be the first digit (i.e. 1 digit)
So, the total number of digits is:
Evaluate the product
Hence, there are 90 4-digit palindromes.
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Step 1) Draw a dashed line through the points (0,6) and (4,7). These two points are on the line y = (1/4)x+6. To find those points, you plug in x = 0 to get y = 6. Similarly, plug in x = 4 to get y = 7. The dashed line indicates that none of the points on this line are part of the solution set.
Step 2) Draw a dashed line through (0,-1) and (1,1). These two points are on the line y = 2x-1. They are found in a similar fashion as done in step 1.
Step 3) Shade the region that is above both dashed lines. We shade above because of the "greater than" sign. This is shown in the attached image I am providing below. The red shaded region represents all of the possible points that are the solution set. Once again, any point on the dashed line is not in the solution set.
Step 2) Draw a dashed line through (0,-1) and (1,1). These two points are on the line y = 2x-1. They are found in a similar fashion as done in step 1.
Step 3) Shade the region that is above both dashed lines. We shade above because of the "greater than" sign. This is shown in the attached image I am providing below. The red shaded region represents all of the possible points that are the solution set. Once again, any point on the dashed line is not in the solution set.
Remember, 
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is circumference and tex]d[/tex] is the diameter. They are related by a constant 
(pi).
We can solve the above equation for d and then substitute our known values.
We can solve the above equation for d and then substitute our known values.