Rounding Decimals 5.NBT.4

Remember This: “Look right next door-if it’s 5 or more (5,6,7,8 or 9) raise (increase by one) the score. If it’s 4 or less (4,3,2,1 or 0) let it rest.

Rounding Decimals to the Thousandths

Rounding to the nearest tenth and Whole Number (Ones place value)

Decomposing a number Decompose 9.949 Ones Tenths Hundredths Thousandths 9 4   99 994 What decomposition of 9.949 best helps to round this number to the nearest tenth? The one using the most tenths to name the decimal fraction. I knew I would round to either 99 tenths or 100 tenths. I looked at the hundredths. Four hundredths is not past the midpoint, so I rounded to 99 tenths. Ninety-nine tenths is the same as 9.9. Which digit made no difference when you rounded to the nearest tenth? Answer: The thousandths, because the hundredths decided which direction to round. Since there are not 5 hundredths, I rounded to the lesser number.

Using a grid to round decimals .67 (almost fills up the entire grid. Show students that they only need .33 to fill the entire grid. Explain that .33 is less than half (.5 or .50) of 0 and 1 and .67(shaded area) is more than .50. We would round .67 would round to 1 whole.

Round 1.32 to the nearest whole number **Remember that we have 13 tenths and 2 hundredths = 1.32 If we are going to round to the nearest whole number, we have to understand that 10 tenths = 1 whole and 20 tenths = 2 whole numbers. Since, we know that the half way point between 10 and 20 tenths is 15 tenths. 13 tenths is less than 15 tenths so would round to 10 tenths which =‘s 1 whole.

Round 49.67 to the nearest tens using a vertical number The different ways 49.67 could be decomposed. On your place value chart, show the decomposition that you think will be most helpful in rounding to the nearest ten. Tens Ones Tenths Hundredths 4 9 6 7   49 496 Decide which one of these decompositions will be the most helpful? The decomposition with more tens is most helpful because it helps me identify the two rounding choices: 4 tens or 5 tens.

Round 32.697 to the nearest tenth, hundredth, and one. (327 tenths) = 32.7 (3270 hundredths) = 32.70 (33 ones) = 33 32.697 32.697 32.697 326 tenths and 5 hundredths = 32.650 3269 hundredths and 5 thousandths = 32.695 32 ones and 5 tenths = 32.5 (326 tenths) = 32.6 (3269 hundredths) = 32.69 (32 ones) = 32