How many positive integers less than 10^20 have all their digit...

For all positive integers x, let x▲ be defined to be (x-1)(x+1). Which of the following is equal to...

How many positive integers in the set {50, 51,, . . . , 298, 299} do not contain any even digits?...

x,y and z are positive integers such that x<y,x+y=201,z−x=200. What is the maximum value of x+y+z?

How many positive odd integers between 100 and 10000 can be formed using the digits 2,3,4,5 and 6

How many positive odd integers less than 500 can be formed from the digits 3, 4, and 5 without repet...

How many positive integers, not having the digit 1, can be formed if the product of all its digits i...

1.How many positive integers five-digit integers end with the digit 0? 9x10x10x10x? what number woul...

How many positive integers less than 100 and divisible by 3 are also divisible by 4?

How many positive integers less than 1000 are there which contain at least one 4 or at least one 9 (...

How many positive integers less than 100 have a reminder of 3 when divided by 7?

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