Column method
125.3 + 145. 2 =
1. First we place both numbers on top of each other with each digit in its correct column (H = hundreds, T = tens, U = units, . = Decimal point, t = tenths ).
Remember: If you are calculating decimal number keep the decimal points in the same column even in your answer line.
2. Start to add together all of the numbers in each column. Make sure you start with the column that is furthest to the RIGHT. In this case it is the Tenths column (t). So we add together the digits in the tenths column: 3 tenths + 2 tenths = 5 tenths (or 0.3 + 0.2 = 0.5) . Then record the amount of tenths just underneath.
3. Now we repeat this with the Units column (U): 5 units + 5 units = 10 (or 5 + 5 = 10). We cannot record ‘10’ in the unit’s column in our answer because you cannot have more than one digit in each column.
10 = ‘1 ten’ therefore we move it into the Tens (T) column. We also have to place a ‘0’ in our units column to show that there are no units (remember that zero is a place holder.)
4. Next we add up all the digits in the Tens column (T). We must also remember to add the 10 we moved from the unit’s column: 1 ten + 2 tens + 4 tens = 7 tens (or 10 + 20 + 40 = 70). Then record the number of tens underneath.
5. Finally we add all the digits in our hundreds column: 1 hundred + 1 hundred = 2 hundred (100 + 100 = 200) . Then write the number of hundreds underneath.
6. And then, BINGO, you have your answer: 270.5
125.3 + 145. 2 =
1. First we place both numbers on top of each other with each digit in its correct column (H = hundreds, T = tens, U = units, . = Decimal point, t = tenths ).
Remember: If you are calculating decimal number keep the decimal points in the same column even in your answer line.
2. Start to add together all of the numbers in each column. Make sure you start with the column that is furthest to the RIGHT. In this case it is the Tenths column (t). So we add together the digits in the tenths column: 3 tenths + 2 tenths = 5 tenths (or 0.3 + 0.2 = 0.5) . Then record the amount of tenths just underneath.
3. Now we repeat this with the Units column (U): 5 units + 5 units = 10 (or 5 + 5 = 10). We cannot record ‘10’ in the unit’s column in our answer because you cannot have more than one digit in each column.
10 = ‘1 ten’ therefore we move it into the Tens (T) column. We also have to place a ‘0’ in our units column to show that there are no units (remember that zero is a place holder.)
4. Next we add up all the digits in the Tens column (T). We must also remember to add the 10 we moved from the unit’s column: 1 ten + 2 tens + 4 tens = 7 tens (or 10 + 20 + 40 = 70). Then record the number of tens underneath.
5. Finally we add all the digits in our hundreds column: 1 hundred + 1 hundred = 2 hundred (100 + 100 = 200) . Then write the number of hundreds underneath.
6. And then, BINGO, you have your answer: 270.5
