Can you prove that there are exactly $90$ elements in the set of numbers having $4$ digits which are palindromes?
This is not a tricky question. I am just trying to understand the concept of proofs better.
2026-03-25 15:52:36.1774453956
Number of 4 digit palindromes
215 Views Asked by Bumbble Comm https://math.techqa.club/user/bumbble-comm/detail At
1
There are 1 best solutions below
Related Questions in COMBINATORICS
- Using only the digits 2,3,9, how many six-digit numbers can be formed which are divisible by 6?
- The function $f(x)=$ ${b^mx^m}\over(1-bx)^{m+1}$ is a generating function of the sequence $\{a_n\}$. Find the coefficient of $x^n$
- Name of Theorem for Coloring of $\{1, \dots, n\}$
- Hard combinatorial identity: $\sum_{l=0}^p(-1)^l\binom{2l}{l}\binom{k}{p-l}\binom{2k+2l-2p}{k+l-p}^{-1}=4^p\binom{k-1}{p}\binom{2k}{k}^{-1}$
- Algebraic step including finite sum and binomial coefficient
- nth letter of lexicographically ordered substrings
- Count of possible money splits
- Covering vector space over finite field by subspaces
- A certain partition of 28
- Counting argument proof or inductive proof of $F_1 {n \choose1}+...+F_n {n \choose n} = F_{2n}$ where $F_i$ are Fibonacci
Related Questions in PROOF-WRITING
- how is my proof on equinumerous sets
- Do these special substring sets form a matroid?
- How do I prove this question involving primes?
- Total number of nodes in a full k-ary tree. Explanation
- Prove all limit points of $[a,b]$ are in $[a,b]$
- $\inf A = -\sup (-A)$
- Prove that $\sup(cA)=c\sup(A)$.
- Supremum of Sumset (Proof Writing)
- Fibonacci Numbers Proof by Induction (Looking for Feedback)
- Is my method correct for to prove $a^{\log_b c} = c^{\log_b a}$?
Related Questions in PALINDROME
- The quotient of two palindromes
- How many $4$-digit palindromes are divisible by $3$?
- Palindrome multiple of prime
- Patterns in solutions to simultaneous palindromes in two number bases
- How many palindromes of length 5 can be formed that contain 7 or 8?
- How to make a palindromic table where each row and column is a palindrome?
- Dynamic Programming problem palindrome
- Prove that a language which consists of concatenation of strings in palindromes is not a regular language?
- How many palindromes are there in the range $0000$ to $9999$?
- When are $a+b$ and $ab$ palindromic for integers $a,b$?
Trending Questions
- Induction on the number of equations
- How to convince a math teacher of this simple and obvious fact?
- Find $E[XY|Y+Z=1 ]$
- Refuting the Anti-Cantor Cranks
- What are imaginary numbers?
- Determine the adjoint of $\tilde Q(x)$ for $\tilde Q(x)u:=(Qu)(x)$ where $Q:U→L^2(Ω,ℝ^d$ is a Hilbert-Schmidt operator and $U$ is a Hilbert space
- Why does this innovative method of subtraction from a third grader always work?
- How do we know that the number $1$ is not equal to the number $-1$?
- What are the Implications of having VΩ as a model for a theory?
- Defining a Galois Field based on primitive element versus polynomial?
- Can't find the relationship between two columns of numbers. Please Help
- Is computer science a branch of mathematics?
- Is there a bijection of $\mathbb{R}^n$ with itself such that the forward map is connected but the inverse is not?
- Identification of a quadrilateral as a trapezoid, rectangle, or square
- Generator of inertia group in function field extension
Popular # Hahtags
second-order-logic
numerical-methods
puzzle
logic
probability
number-theory
winding-number
real-analysis
integration
calculus
complex-analysis
sequences-and-series
proof-writing
set-theory
functions
homotopy-theory
elementary-number-theory
ordinary-differential-equations
circles
derivatives
game-theory
definite-integrals
elementary-set-theory
limits
multivariable-calculus
geometry
algebraic-number-theory
proof-verification
partial-derivative
algebra-precalculus
Popular Questions
- What is the integral of 1/x?
- How many squares actually ARE in this picture? Is this a trick question with no right answer?
- Is a matrix multiplied with its transpose something special?
- What is the difference between independent and mutually exclusive events?
- Visually stunning math concepts which are easy to explain
- taylor series of $\ln(1+x)$?
- How to tell if a set of vectors spans a space?
- Calculus question taking derivative to find horizontal tangent line
- How to determine if a function is one-to-one?
- Determine if vectors are linearly independent
- What does it mean to have a determinant equal to zero?
- Is this Batman equation for real?
- How to find perpendicular vector to another vector?
- How to find mean and median from histogram
- How many sides does a circle have?
Hint: a four-digit palindrome must look like $ABBA$ where $A$ and $B$ are digits, and $A$ is nonzero. The number of ways can you choose $A$ and $B$ is the number of four-digit palindromes.