Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23 ?
Is it possible to write down 1,2,3..100 in some order (one after an other), such that the sum of any two adjacent numbers is a prime number?
? + ? + ? + ? + ? = 30
You have to fill numbers in place of question marks. The numbers that you can use are 1, 3, 5, 7, 9, 11, 13 and 15. You can repeat the numbers if you like.
Using the digits 1, 2, 3 and 4, find the number of 10-digit sequences that can be written so that the difference between any two consecutive digits is 1.
Examples of such 10-digit sequences are ********** and **********.