Decimal Addition to Hundredths: Align decimal points and add each column including hundredths
- Align decimal points in columns
- Add digits in each column from right to left
- Carry over when sum ≥ 10
- Place decimal point in the answer
Write the numbers so that decimal points are in the same column
+2.78
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6 + 8 = 14, write down 4 and carry over 1
+2.78
-----
.4
¹
5 + 7 + 1 (carry) = 13, write down 3 and carry over 1
+2.78
-----
.34
¹¹
4 + 2 + 1 (carry) = 7
+2.78
-----
7.34
4.56 + 2.78 = 7.34
• Decimal Alignment: Always align decimal points when adding/subtracting
• Carrying: When sum ≥ 10, carry the tens digit to the next column
• Place Value: Each column represents hundredths, tenths, units, etc.
Decimal Subtraction to Hundredths: Align decimal points and subtract each column including hundredths
Write the numbers so that decimal points are in the same column
-4.78
-----
4 - 8: Since 4 < 8, borrow 1 from tenths column (3 becomes 2, 4 becomes 14)
14 - 8 = 6
6.34
-4.78
-----
.6
2 - 7: Since 2 < 7, borrow 1 from units column (6 becomes 5, 2 becomes 12)
12 - 7 = 5
6.²¹⁴
6.34
-4.78
-----
.56
5 - 4 = 1
6.²¹⁴
6.34
-4.78
-----
1.56
6.34 - 4.78 = 1.56
• Decimal Alignment: Always align decimal points when adding/subtracting
• Borrowing: When top number < bottom number, borrow from the next higher place value
• Place Value: Each column represents hundredths, tenths, units, etc.
Different Decimal Places: Add zeros to make all numbers have the same number of decimal places
Add zeros to 5.7 to match the number of decimal places in 3.46
5.7 becomes 5.70
+3.46
-----
Write the numbers so that decimal points are in the same column
0 + 6 = 6
+3.46
-----
.6
7 + 4 = 11, write down 1 and carry over 1
+3.46
-----
.16
¹¹
5 + 3 + 1 (carry) = 9
+3.46
-----
9.16
5.7 + 3.46 = 9.16
• Equalizing Decimals: Add zeros to make all numbers have same decimal places
• Decimal Alignment: Always align decimal points
• Carrying: When sum ≥ 10, carry to next column
Decimal Point: Separates whole numbers from fractional parts
Tenths: First digit after decimal point (1/10)
Hundredths: Second digit after decimal point (1/100)
Borrowing to Hundredths: When subtracting decimals, sometimes you need to borrow from multiple place values
Write the numbers so that decimal points are in the same column
-5.67
-----
3 - 7: Since 3 < 7, need to borrow. But tenths column has 0, so borrow from units column first.
8 (units) becomes 7, 0 (tenths) becomes 10. Now borrow from tenths: 10 becomes 9, 3 becomes 13
13 - 7 = 6
8.03
-5.67
-----
.6
9 - 6 = 3
8.03
-5.67
-----
.36
7 - 5 = 2
8.03
-5.67
-----
2.36
8.03 - 5.67 = 2.36
• Decimal Alignment: Always align decimal points when adding/subtracting
• Multiple Borrowing: When borrowing from zero, continue borrowing from next non-zero column
• Place Value: Each column represents hundredths, tenths, units, etc.
Decimals with Zeros: Handle zeros in the middle of decimal numbers the same way as other digits
Write the numbers so that decimal points are in the same column
+4.50
-----
8 + 0 = 8
+4.50
-----
.8
0 + 5 = 5
+4.50
-----
.58
7 + 4 = 11, write down 1 and carry over 1
+4.50
-----
1¹.58
¹
0 + 0 + 1 (carry) = 1
+4.50
-----
11.58
7.08 + 4.50 = 11.58
• Decimal Alignment: Always align decimal points
• Place Value: Treat zeros like any other digit
• Carrying: When sum ≥ 10, carry to next column