Decimal Addition: Line Up All Decimal Points

Adding decimal numbers in columns is just like adding whole numbers in columns. Please be sure you understand the unit Column Addition before you continue with this unit Decimal Addition.

We need to do only one thing that we didn't do in the unit Column Addition: Line Up All Decimal Points.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

Right To Left. Going from right to left, 0.00041 is the only number that has an entry in the hundred thousandths place. We put this 1 in the answer (sum):

Right To Left. In the ten thousandths place, 4 + 9 = 13:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

As we see above, the 1 in 13 is carried. This is the only entry in the thousandths column:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

The 1 in 0.6109 is the only entry in the hundredths column:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

In the tenths column, 4 + 6 = 10:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

In the units column, 1 + 8 + 8 = 17:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

In the tenths column, 1 + 6 + 5 = 12:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

In the hundreds column, 1 + 3 + 2 = 6:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box

In the thousands column, we bring down the 7 of 7258:

0
.
0
0
0
4
1

3
6
8
.
4

0
.
6
1
0
9
+
7
2
5
8
.

White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box   White Box