1. Decimals What is a decimal? Do you know?

2. A decimal is… Written just like a period Part of a whole

3. Today we will use money to understand decimals. Think of a whole dollar bill. Is there any amount of money less than a dollar?

4. Of course there is! Half Dollars Quarters Dimes Nickels Pennies

5. Money is written in decimals. To write this amount of money, we must use a decimal to show whole dollars and parts of a dollar. Let’s count the money! $2.73 Two dollars and seventy three cents

6. What part of a dollar are the coins? This is a half dollar. It is half of a dollar. It is 50 hundredths of a dollar. It is worth 50 cents. This is a quarter. It takes 4 quarters to make a dollar and is 25 hundredths of a dollar. It’s worth 25 cents. This is a dime. It takes 10 dimes to make a dollar and is 1 tenth of a dollar. It’s worth 10 cents. This is a nickel. It takes 20 nickels to make a dollar and is 5 hundredths of a dollar. It’s worth 5 cents. This is a penny. It takes 100 pennies to make a dollar and is 1 hundredths of a dollar. It’s worth 1 cent.

7. Because a quarter is worth 25 cents, it is part of a dollar. It is written $0.25. Do you see that there are no whole dollar represented? That’s why we have a zero. The number 25 is behind the decimal. When a number is behind the decimal, it means it’s part of the whole. How many quarters would it take to make a dollar?

8. It would take 4 quarters to make a dollar. One quarter is written $0.25. Two quarters is written $0.50. Three quarters is written $0.75. How about 4 quarters? How would that be written? Remember 4 quarters is equal to one dollar. Would there be anything behind the decimal? $1.00 Since 4 quarters equals a WHOLE dollar, we do not have any parts of a dollar.

9. Now let’s talk about place value in decimals. Ten millions Millions Hundred thousands Ten thousands ThousandsHundreds TensOnesDecimalTenths Hundredths This place value chart looks very similar to the place value chart we saw last week. What’s different?

10. Right! There’s a decimal and you see the words, tenths and hundredths. Ten millions Millions Hundred thousands Ten thousands ThousandsHundreds TensOnesDecimalTenths Hundredths To write an amount of money, we can use a place value chart. Let’s add $3,456.82 to our chart. 345682 We have a lot of money here! We have 3,456 whole dollars. But what does.82 mean? It means part of a dollar, 82 cents!

11. To say this amount is money, we say three thousand, four hundred fifty-six dollars and eighty-two cents. Ten millions Millions Hundred thousands Ten thousands ThousandsHundreds TensOnesDecimalTenths Hundredths 345682 Today, we are going to learn to say this amount differently. First say the whole number: three thousand, four hundred fifty-six. Then where you see the decimal, say “and”, then say eighty-two…now look at the place value chart…where the 2 is. What word is above it? Hundredths. After 82 say, “hundredths”. Put it all together. Three thousand, four hundred fifty-six AND eighty-two hundredths.

12. Let’s try a few more! Ten millions Millions Hundred thousands Ten thousands ThousandsHundreds TensOnesDecimalTenths Hundredths 4 5 7 2 5 9 5 1 8 3 1 3 0 0 2 9 9 2 3 4 8 7 5 3 9 9 5 7 0 0 1 8 6 6 7 2 9