Integer Division

Part of the First Circuits section of Coddy's Arduino journey. Lesson 15 of 22.

When both sides of / are whole numbers, the answer is a whole number too. The fraction is dropped, not rounded: 7 / 2 is 3, and 19 / 10 is 1.

The part that was dropped is what % gives you: 7 % 2 is 1. Together they answer "how many fit, and how many are left over".

Serial.println(7 / 2);    // 3
Serial.println(7 % 2);    // 1
Serial.println(7.0 / 2);  // 3.50

To keep the fraction, write one of the numbers with a decimal point. 7.0 is a decimal number, and dividing with a decimal number gives a decimal answer: 3.5. Serial.println() shows decimal numbers with two digits after the point, so it prints 3.50.

Challenge

Easy

17 sweets are shared between 5 children. In setup(), print three lines:

how many sweets each child gets: 17 / 5
how many are left over: 17 % 5
the exact share as a decimal: 17.0 / 5

Press Run, then Check.

Try it yourself

void setup() {
  Serial.begin(9600);
  // each child's share, what is left over, the exact share
}

void loop() {
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in First Circuits

1Hello, Board

Blink an LED Setup and Loop Change the Blink Speed An LED of Your Own Two LEDs Taking Turns Comments in Your Sketch

4Decisions

Decisions with if Choosing with if and else Comparing Values Combining Conditions Read a Button

2Talking to Your Computer

Hello, Serial Monitor Print Versus Println Printing Numbers Your First Variable Counting Up When an Int Runs Out

3Math on the Board

Named Constants Arithmetic OperatorsInteger DivisionDecimals with float A Blink That Speeds Up

Practice on your own: Arduino playground