6.2.4 Adding & Subtracting Decimals

Base Ten Blocks = 1 one = 1 tenth = 1 hundredth = 1.00 = .10 = .01 = 1 Dollar = 1 Dime = 1 Penny

Combining Blocks = 1 one, 2 tenths, 3 hundredths = 1.00 + .20 + .03 = 1.23 = 0 one, 8 tenths, 7 hundredths = 0.00 + .80 + .07 = 0.87

Adding Blocks How many tenths are there? 10 How many hundredths are there? + Can the hundredths or tenths be traded up? YES!

Trading Up = 10 hundredths = = + 1 tenth + = 10 tenths = 1 one

Putting It All Together 1 one + 1 one = 2 ones + 1 ten = 2 ones and 1 ten = 2.10 1.23 + 0.87 = 2.10

Adding & Subtracting Decimals Step #1: Line up the decimals Step #2: Add or subtract as usual (as if the decimal isn’t there) 1.23 4.93 5.13 13.02 1.562 83.003 + .87 + 2.71 – .19 – 9.74 +4.08 . –55.1009 2.10 7.64 4.94 3.28 5.642 27.9021

Your Turn! 88.44 + 21.01 90.31 – 72.04 10 + 732.77 17 – 58.23 101.3 + 43.0106 90.003 – 86.1

Homework Page 82 (3, 4, 5, 9, 11, 16, 17, 18, 19, 20, 24, 26, 30, 31)