Chapter 1 · Lesson 3 of 5
03. Numbers and sums
Java can do sums. Print them and it shows the answer, and join numbers to words with +.
Numbers go straight into println, without quotes. If you give it a sum, Java works it out first and prints the answer. Join words and numbers with +: put the sum in brackets so it's worked out before it's joined.
public class Main { public static void main(String[] args) { System.out.println(12); System.out.println(7 + 5); System.out.println("6 times 7 is " + (6 * 7)); System.out.println("Oops: " + 7 + 5); }}It shows
12 12 6 times 7 is 42 Oops: 75
See the last line? Without brackets, Java joins left to right: "Oops: " + 7 makes the text Oops: 7, then + 5 adds 5 on the end. Brackets fix it.
Use + and - as usual, * to multiply, / to divide, and % for what's left over after dividing.
Your turn
1Steps
- 1A school hall has 18 rows of 25 chairs. Print
Chairs:and the number of chairs, worked out by Java with*. - 2Then print
Seconds in an hour:and60 * 60, also worked out by Java.
Write it in Main.java, in public class Main. If it reads input, put the answers in Program input, under the terminal.
Use: System.out.println
Starting code
The editor starts empty. Copy this into it to begin, or write your own from scratch.
public class Main { public static void main(String[] args) { System.out.println("Chairs: "); }}2Expected output
It should show
Chairs: 450 Seconds in an hour: 3600
3Hints
Stuck? Open one hint at a time: each gives a bit more help.
Hint 1
Join the words and the sum with +, and put the sum in brackets.
Hint 2
The first line is System.out.println("Chairs: " + (18 * 25));
Hint 3
The second is made the same way, with 60 * 60.