03. Numbers and sums

C can do sums. Show the answers with printf and %d, the placeholder for a whole number.

To show a number, put %d in the text where it should go, then the number after a comma. %d is a placeholder: printf swaps it for the number.

1#include <stdio.h>2
3int main() {4    printf("I have %d mangoes\n", 12);5    printf("7 + 5 = %d\n", 7 + 5);6    printf("%d times %d is %d\n", 6, 7, 6 * 7);7    return 0;8}

It shows

I have 12 mangoes
7 + 5 = 12
6 times 7 is 42

C works out the sum first, then prints the answer. Use + and - as usual, * to multiply and / to divide. With several %ds, the numbers after the text fill them in order.

Your turn

1Steps

1A school bus has 4 rows of 9 seats. Print Seats: and the number of seats, worked out by C with *.
2Then print Hours in a week: and 24 * 7, also worked out by C.

Write it in main.c. If it reads input, put the answers in Program input, under the terminal.

Use: printf()

Starting code

The editor starts empty. Copy this into it to begin, or write your own from scratch.

1#include <stdio.h>2
3int main() {4    printf("Seats: \n");5    return 0;6}

2Expected output

It should show

Seats: 36
Hours in a week: 168

3Hints

Stuck? Open one hint at a time: each gives a bit more help.

Hint 1

Put %d where the number goes, and the sum after a comma.

Hint 2

The first line is printf("Seats: %d\n", 4 * 9);

Hint 3

The second is made the same way, with 24 * 7 after the comma.