Question

4. I. Write a MATLAB code to find whether a given positive integer is a perfect number or not. A perfect number is a positive integer that is equal to the sum of its proper divisors. II. Write a MATLAB code to find the number of digits of a given positive integer. III. Consider the vector ? = −10, −7, −4, … , 14. Replace all negative entries with zeros.

Answer 1

% 1)
n = input("Enter a positive integer: ");
total = 0;
for i=1:n-1
    if mod(n, i) == 0
        total = total + i;
    end
end

if total == n
    fprintf("%d is a perfect number\n", n)
else
    fprintf("%d is not a perfect number\n", n)
end

% 2)
n = input("Enter a positive integer: ");
if n < 0
    n = -1*n;
end
count = 0;
while n > 0
    n = floor(n / 10);
    count = count + 1;
end
fprintf("Number of digits is %d\n", count)

% 3)
x = -10:3:14
for i=1:length(x)
    if x(i) < 0
        x(i) = 0;
    end
end
x