Decimal Rules
What is the rule when adding decimals?
The decimals must line up.
0.4 + 1.1 =
1.5
3.2 - 1.1 =
2.1
3 x 0.5 =
1.5
3.5
Three and five tenths
What is the rule when subtracting decimals?
The decimals must line up.
1.23 + 4.5 =
1.68
5.31 - 4.2 =
1.11
4.2 x 3 =
12.6
0.7
Seven Tenths
What is the rule when multiplying decimals?
Count the number of spaces you move the decimal.
2.5 + 1.7 =
4.2
8.5 - 3.9 =
4.6
3.5 x 2 =
7
4.15
Four and Fifteen Hundredths
How many decimal places do you move in this problem?
4.1 x 2.2 =
4.3 + 1.95 =
6.25
61.2 - 4.1 =
57.1
2 x 6.1 =
12.2
258.4
Two Hundred Fifty Eight and Four Tenths
How many decimal places do you move in this problem?
4.35 x 15.1
6 + 3.08 =
9.08
18 - 3.5 =
14.5
3.4 x 6 =
20.4
100.55
One Hundred and Fifty Five Hundreths.