Kotlin Program:

Example:

import java.util.Scanner

fun binary(num:Int):Boolean {
  var n=num
  while(n!=0) {
    if(n%10==0 || n%10==1)
      n/=10
    else return false
  }
  return true
}

fun main(args: Array<String>) {

  val userInput = Scanner(System.`in`)
  print("Enter your number : ")
  var num:Int = userInput.nextInt()

  if(binary(num))
    println("Number is in binary form")
  else 
    println("Number is not in binary form")
}

Output:

  Enter Your number : 1101
  Number is in binary form

Binary Numbers : Numbers with only 0 & 1 combination

Examples like: 101, 111, 10, 11111

Main Logic :

fun binary(num:Int):Boolean {
  var n=num
  while(n!=0) {
    if(n%10==0 || n%10==1)
      n/=10
    else return false
  }
  return true
}

Divide the number by 10 while your number becomes 0[ZERO] &
In-between check, is there any remainder other than 0 & 1