The square root of a number can be calculated by repeated subtraction method provided the number is an integer square number. In repeated subtraction method successive odd numbers are subtracted from the given whole square number until zero is obtained. Then the total quantity of numbers which are subtracted in all steps are the square root of that number. The Octave code for calculating the square root of 100 and 169 is given below.

Octave code:

function sqrroot = sqrrootbyrepetativesub(number)

  i=1; sqrroot = 0;

while number ~= 0

  number = number - i;

  sqrroot = sqrroot + 1;

  i = i+2;

end

endfunction

Now, calling the function with numbers 100 and 169 the square roots are obtained.

Output:

>> sqrroot = sqrrootbyrepetativesub(100)

sqrroot =  10

>> sqrroot = sqrrootbyrepetativesub(169)

sqrroot =  13