How many 3-digit positive integers are there whose middle digit is equal to the sum of the first and last digits? How many positive three-digit numbers can be made from the digits 4, 5, 6, and 7 if no digit can be used more than once in a given number?
60. How many 7-digit palindromes (numbers that read the same backward as forward) can be formedusing the digits 2,2,3,3,5,5,5?()(A)6(B)12(C)24(D)36 相关知识点: 试题来源: 解析 60.A解:七位的回文数应是形如abcdcba,很显然d=5。剩下的问题就是abcdcba的前三位abc有几种可能性?
How many subsets of 3 distinct integers from 1, 2, 3, . . . , 90 are there whose sum of integers is divisible by 3? How many 4-digit numbers cannot be divided by 5? How many positive three-digit integers can be written in such a way that the first digit is greate...
For example, each of the following five-digit integers are palindromes: 12321, 55555, 45554 and 11611. Write a program that reads in a five-digit integer and deter- mines whether or not it is a palindrome. [Hint : Use the division and remainder operators to separate the number into its...
For this next section, you’re going to build a program that makes use of all three methods. This program will print numeric palindromes like before, but with a few tweaks. Upon encountering a palindrome, your new program will add a digit and start a search for the next one from there....
Palindromes: A palindrome is a word or phrase that reads the same forwards and backwards. The cryptic part of the clue will generally just clue you in that it is a palindrome. (In the explanation, this will be marked with > and < symbols.) ...
For this next section, you’re going to build a program that makes use of all three methods. This program will print numeric palindromes like before, but with a few tweaks. Upon encountering a palindrome, your new program will add a digit and start a search for the next one from there....
How many bit strings are there of length 6 which contain exactly three 1's? A station is to be assigned a three-letter call sign. if the first letter must be an upper k or upper w, how many three-letter call signs are possible? How many pai...
How many nodes are there in a complete binary tree of depth 6? A palindrome is a string that can be read the same both front and back. For example, abba, gogog, and Malayalam are palindromes. How many palindromes of length 11 are there whose characters come from (a, b, c, ... ...
How many three digit numbers contain at least one digit that is a 7? How many subsets are there in a set with 10 elements? You are given 5 integers. Prove that it is possible to choose three of them in such a way that their sum is divisible by 3. ...