Decimal Subtraction: Line Up All Decimal Points

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

Subtracting decimal numbers in columns is just like subtracting whole numbers in columns. Please be sure you understand the unit Column Subtraction before you continue with this unit Decimal Subtraction.

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

Let's subtract the following numbers:

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

2
5
8
0
.
0
2
6
7
1
.
7
4
9
2

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   White Box   White Box   White Box   White Box   White Box

2
5
8
0
.
0
2
6
7
1
.
7
4
9
2

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, we see that 7 - 2 = 5:

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

2
5
8
0
.
0
2
6
7
1
.
7
4
9
2

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

Right To Left. We cannot do 6 - 9. We cannot do 2 - 4. We cannot do 0 -7. We can do 8 - 1 and also, 8 - 1 lets us do regrouping:

We bring down the 5 in the tenths columns and the 2 in the hundreds column: