Decimals
Maths: Edexcel IGCSE Higher, topic 1.3.1
Place Value
When a number is written out in digits each number stands for a different value depending on what position it takes in the number. For example in the number 7,342,176.525:
Hundreds
- The number 1 stands for 100 since it is in the hundreds place.
Hundreds of thousands
- The number 3 stands for 300,000 since it is in the hundreds of thousands place.
Adding Decimals
You should be able to add decimals without a calculator.
Step 1
- Move the decimal point two digits to the right (multiply by 100).
- This gets rid of the decimals and lets us work with whole numbers.
Step 2
- Add the whole numbers together.
Step 3
- Re-introduce the decimals.
- Move the decimal point two digits to the left (divide by 100).
Answer
Subtracting Decimals
You should be able to subtract decimals without a calculator.
Step 1
- Move the decimal point one digit to the right (multiply by 10).
- This gets rid of the decimals and lets us work with whole numbers.
Step 2
- Calculate the difference between the whole numbers.
Step 3
- Re-introduce the decimals.
- Move the decimal point one digit to the left (divide by 10).
Answer
Test yourself on Decimals
What does the 6 stand for in 8,375,693.1?
What does the 5 stand for in 8,375,693.1?
What does the 1 stand for in 8,375,693.1?
What does the 7 stand for in 7,414,311.8?
What does the 3 stand for in 7,414,311.8?