When it comes to decimals, 9th graders in Sweden should learn some important skills to build a solid base in math. Let’s take a closer look at these skills!

1. Adding and Subtracting Decimals

When you add or subtract decimals, it’s important to line up the decimal points. Here are a couple of examples:

• $3.5 + 2.67 = 6.17$
• $5.4 - 1.25 = 4.15$

Always keep the decimal points lined up. This helps avoid mistakes.

2. Multiplying Decimals

Multiplying decimals might seem hard at first, but it’s actually simple once you practice. Just multiply them like regular whole numbers, and then place the decimal point in the right spot:

• For example, $0.3 \times 0.2 = 0.06$
• Here’s how it works: First, do $3 \times 2 = 6$. Then move the decimal point two places to the left because there are two decimal places in total.

3. Dividing Decimals

Dividing decimals is a bit different. You need to turn the number you are dividing by (the divisor) into a whole number. Move the decimal point over, and do the same for the number you’re dividing (the dividend):

• For example, $1.2 \div 0.4$ can be changed to $12 \div 4 = 3$.

4. Changing Fractions to Decimals and Vice Versa

It’s important to know how to switch between fractions and decimals. For example:

• The fraction $\frac{1}{4}$ turns into $0.25$ (because $1 \div 4 = 0.25$).
• On the other hand, $0.75$ can change back to the fraction $\frac{3}{4}$.

By learning these skills and changing between fractions and decimals, students will be ready to take on harder math problems in Year 9 and beyond!