Squares and Cubes of Two-Digit Odd Numbers in C

This C program prints the square and cube of every two-digit odd number — that is, the odd numbers from 11 to 99. A number is odd if it is not divisible by 2 (n % 2 != 0). Two-digit odd numbers begin at 11 (the smallest two-digit odd) and end at 99.

The original post had only a GitHub Gist shortcode — no actual code in the page. This rewrite provides the complete program, a formula reference, and a partial output table.

Formulas

Value	Formula	Example (n=11)	Example (n=99)
Square	n × n = n²	11 × 11 = 121	99 × 99 = 9801
Cube	n × n × n = n³	11 × 11 × 11 = 1331	99 × 99 × 99 = 970299

C Program: Squares and Cubes of Two-Digit Odd Numbers

/* Squares and cubes of all two-digit odd numbers (11–99)
 * Compile: gcc -ansi -Wall -Wextra squarescubes.c -o squarescubes */
#include <stdio.h>

int main(void)
{
    int n;

    printf("%-8s %-10s %-12s\n", "Number", "Square", "Cube");
    printf("%-8s %-10s %-12s\n", "------", "------", "----");

    for (n = 11; n <= 99; n += 2) {
        printf("%-8d %-10d %-12d\n", n, n * n, n * n * n);
    }

    return 0;
}

How to Compile and Run

gcc -ansi -Wall -Wextra squarescubes.c -o squarescubes
./squarescubes

Sample Output (first 10 rows)

Number   Square     Cube
------   ------     ----
11       121        1331
13       169        2197
15       225        3375
17       289        4913
19       361        6859
21       441        9261
23       529        12167
25       625        15625
27       729        19683
29       841        24389
...
99       9801       970299

Code Explanation

for (n = 11; n <= 99; n += 2) — starts at 11 (the first two-digit odd) and steps by 2 each iteration, which always produces odd numbers. Stepping by 2 from any odd number gives the next odd number: 11→13→15→…→99. There are 45 two-digit odd numbers in total.
n * n for square, n * n * n for cube — direct multiplication in C. The compiler optimizes these with no performance concern for small n. An alternative is to compute sq = n * n once and reuse it as sq * n for the cube.
%-8d %-10d %-12d formatting — the minus sign left-aligns within the field width. This produces aligned columns. Without it, numbers are right-aligned (default): 8-character column for the number, 10-character for the square, 12-character for the cube (needed for 99³ = 970299, six digits).
Why start at 11, not 1? — Two-digit numbers are 10–99. The number 10 is even, so the first two-digit odd number is 11. Single-digit odd numbers (1, 3, 5, 7, 9) are excluded.

Variation: Check a Single Number

To check one specific number entered by the user:

int main(void)
{
    int n;
    printf("Enter a number: ");
    scanf("%d", &n);
    if (n >= 11 && n <= 99 && n % 2 != 0)
        printf("%d: square=%d, cube=%d\n", n, n*n, n*n*n);
    else
        printf("%d is not a two-digit odd number.\n", n);
    return 0;
}

What This Program Teaches

Stepping a for loop by 2 — n += 2 is a compact way to iterate over all odd (or all even) numbers in a range. It’s twice as fast as checking n % 2 != 0 inside a loop that steps by 1.
Column-aligned output with printf — the %-Nd format (negative width = left-align) makes tabular output readable. This is the manual equivalent of using tabs, but with controlled column widths.
Integer arithmetic for power — in C, pow(n, 3) works but returns double. For integer exponents, direct multiplication (n*n*n) is more accurate (no floating-point rounding) and does not require linking -lm.
Two-digit number range — the numbers 10–99 form the “two-digit” set. Starting at 11 and stepping by 2 generates exactly the two-digit odd subset without any extra checks inside the loop.

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C Program to find the squares and cubes of a two digit odd number.