Adding decimals is almost as easy as adding whole numbers. We need to pay extra attention to place values, and we must never write extra zeros, which is a waste of time.
Let us try 6.7 + 5.3. Regrouping, we have (6 + 5) ones plus (7 + 3) tenths. Simplifying, we have 11 ones + 10 tenths, or 12 ones. The answer is 12.
Now let us try 1.6 + 2.1 + 12.3. Regrouping, we have 1 ten, plus (1 + 2 + 2) ones, plus (6 + 1 + 3) tenths. Simplifying, we have 1 ten + 5 ones + 10 tenths, or 10 + 5 + 1. The answer is 16.
Let us try 17.23 + 1.18 + 10.39. Working from right to left, we have (3 + 8 + 9) = 20 hundredths. We do not write the zero in the hundredths place. We regroup the 2 with the tenths.
So (2 + 1 + 3) plus the regrouped 2 tenths = 8 tenths. We write an 8 with a decimal to its left.
Then we have (7 + 1 + 0) ones, or 8 ones. We write the 8 to the left of the decimal.
Then we have (1 + 1) tens, or 2 tens. We write the 2 at the left. The answer is 28.8.
Let us try 6.7 + 5.3. Regrouping, we have (6 + 5) ones plus (7 + 3) tenths. Simplifying, we have 11 ones + 10 tenths, or 12 ones. The answer is 12.
Now let us try 1.6 + 2.1 + 12.3. Regrouping, we have 1 ten, plus (1 + 2 + 2) ones, plus (6 + 1 + 3) tenths. Simplifying, we have 1 ten + 5 ones + 10 tenths, or 10 + 5 + 1. The answer is 16.
Let us try 17.23 + 1.18 + 10.39. Working from right to left, we have (3 + 8 + 9) = 20 hundredths. We do not write the zero in the hundredths place. We regroup the 2 with the tenths.
So (2 + 1 + 3) plus the regrouped 2 tenths = 8 tenths. We write an 8 with a decimal to its left.
Then we have (7 + 1 + 0) ones, or 8 ones. We write the 8 to the left of the decimal.
Then we have (1 + 1) tens, or 2 tens. We write the 2 at the left. The answer is 28.8.
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