C++ Programming Code Examples C++ > Mathematics Code Examples Find Armstrong number in C++ with logic explanation and code dry run Find Armstrong number in C++ with logic explanation and code dry run What is Armstrong number? A number in which the sum of cube of its individual digits is equal to the number itself is called Armstrong number For Example: 1^3 + 5^3 + 3^3 = 153 4 * 4 * 4 + 0 * 0 * 0 + 7 * 7 * 7 = 407 is an Armstrong number. C++ program which takes input a number and check whether it is Armstrong Number or not To make logic firstly concept about Armstrong number should be very clear We took some variables in which we take input, make calculations and produce results Program take input number in variable num and store it in check variable In for loop we take mod of num with 10 and stores it in variable Armstrong then we divide it with 10(below dry running will make more clear the working) Then we take cubes of Armstrong variable and add it into result variable When num=0; then for loop break after for loop using if else statement we test if our result equals to check variable then number is Armstrong else not. #include<iostream> using namespace std; int main() { int armstrong=0,num=0,result=0,check; cout<<"Enter Number to find it is an Armstrong number?"; cin>>num; check=num; for(int i=1;num!=0;i++){ armstrong=num%10; num=num/10; armstrong=armstrong*armstrong*armstrong; result=result+armstrong; } if(result==check){ cout<<check<<" is an Armstrong Number"; } else{ cout<<check<<" is NOT an Armstrong Number"; } return 0; }