Idea 7of 23Builds onA zero holds the place
Decimals in expanded form
How can you split 12.79 into what each digit is worth?
Today you'll discover
- what each digit of 12.79 is worth
- how to write a decimal as a sum
- how to write it as digits times places
Think first12.79 in a place-value chart
What is the 7 in 12.79 worth?
Decide first, then press Next. Read the place name over each digit.
A place-value chart holding 12.79. A row under it shows what each digit is worth: 10, 2, 0.7, 0.09. Then the sum 12.79 = 10 + 2 + 0.7 + 0.09, and under it each digit times its place. The last step shows 74.28.
See the whole ideathe big idea and the key word, in one place
The big idea
Expanded form adds what each digit is worth: 12.79 = 10 + 2 + 0.7 + 0.09.
Three ways to split 74.28
Expanded form: 70 + 4 + 0.2 + 0.08. Expanded notation: (7 × 10) + (4 × 1) + (2 × 0.1) + (8 × 0.01).
- Tens70
- Ones4
- Tenths0.2
- Hundredths0.08
Easy to get wrongA zero digit adds nothing, so it can be left out of the sum: 5.07 = 5 + 0.07.
Key words
- expanded form
- a number written as the sum of what each digit is worth: 10 + 2 + 0.7 + 0.09
- expanded notation
- each digit times its place value, added up: (7 × 0.1) + (9 × 0.01)
Ready to use it?
- Write a decimal in expanded form.
- Find the number from its expanded form.