Week 4: Arithmetic operators

Arithmetic operators let a C program calculate with numbers. + adds, - subtracts, * multiplies and / divides. % gives the remainder left over after a division, and = stores a value in a variable. This week you learn to type all six symbols on the US English layout, so your calculations come out written correctly.

What you will learn

On the US English layout:

• +: the = key with Shift. Press Shift with the opposite pinky, and press the = key with your right pinky.
• -: the - key, with your right pinky.
• *: the 8 key with Shift. Press Shift with the opposite pinky, and press 8 with your right middle finger.
• /: the / key, with your right pinky.
• =: the = key, with your right pinky.
• %: the 5 key with Shift. Press Shift with the opposite pinky, and press 5 with your left index finger.

A quick example: 7 / 2 gives 3 in C. Both numbers are whole numbers, so the result is a whole number and the decimal part is dropped.

Technique tips

• Put spaces around operators, as in a + b. The spacing makes each line easier to read and check.
• Your right pinky handles -, /, = and +, so keep it close to the home row between presses.
• Return your fingers to the home row after each operator, so the next number is easy to reach.
• The percent sign shares a key with 5. Check the screen after you type it to make sure you got the right symbol.

Lessons

1. Lesson 1, learn (10 to 15 minutes): Watch the six symbols on the keyboard demo. Type each one five times, paying attention to Shift.
2. Lesson 2, practice (10 to 15 minutes): Type short expressions such as a + b, a - b, a * b, a / b and a % b. Focus on getting every symbol right, not on speed.
3. Lesson 3, review (10 to 15 minutes): Take the two-minute test with arithmetic lines. Save your result and practice the symbols you missed.

This week’s goal

This week’s target is 14 WPM and 91% accuracy. Finishing the week’s lessons earns you 1 star. Reach 91% accuracy for 2 stars, and also reach 14 WPM for 3 stars. Focus on accuracy first, because one wrong symbol spoils a line you typed quickly.