Adding Decimals

Review…what is a decimal?

How Can I Model Decimal Addition? We can model decimal addition with a 100s grid! = 0.01  one hundredth = 0.1  one tenth = 1.0  one whole

How do we put them together? Example… 0.32 + 0.6 How do we put them together?

How do we put them together? Example… 0.32 + 0.6 = + 0.92 How do we put them together?

What if my decimal is bigger than 1? 1.26 + 1.37 + How do we put them together?

What if my decimal is bigger than 1? Step 1 - Color in your first addend 1.27

What if my decimal is bigger than 1? Step 2 - Color in the whole number of the 2nd addend So far, I have filled in 1.26 + 1.0

What if my decimal is bigger than 1? Step 3 - Combine the decimal parts of each addend into one grid. 1.26 + 1.37 = 2.63

What if I run out of room? 0.41 + 0.72

What if I run out of room? 0.41 + 0.72 Complete the problem like before. Fill in the grid until you run out of room. So far, I have filled in 0.41 + 0.59

What if I run out of room? 0.41 + 0.72 After your grid is full, begin coloring in another grid to finish the problem. 0.41 + 0.72 = 1.13

How do I use my computation to solve? To find the sum, rewrite numbers so that the decimal point lines up vertically. If the decimal point is out of sight, the decimal point is at the right. Place zeros behind the decimal point if needed. Add like normally. Place the decimal point directly below the decimal point in the problem. 0.32 +0.60 0.92 .

Now you try… Use computation and modeling to solve this addition problem… 2.3 + 1.65 2.30 +1.65 3.95 = 3.95