Fractions: Adding with Unlike Denominators

Remember! When the DENOMINATORS (number at bottom) are different, you must use multiplication to change them into the same denominators by finding common multiples. Then multiply the NUMERATOR (number at top) by the same number. Then just add the numerators. Simplify with division if necessary. Remember! Whatever you do to the top, do to the bottom.
Name ________________________________

Date ________________________________

Time: ________________________________
Example 1
Example 2
       
1.
3 x3 =
9
 
___
____
 
5 x3 =
15
 
3 =
3
+
_____
____
15 =
15
12
divide 3 =
4
____
____
15
divide 3 =
5
2.
1 x3 =
3
 
___
____
 
4 x3 =
12
 
1 x2 =
2
+
___
____
6 x2 =
12
5
____
12
3.
3
 
 
_____
 
 
6
 
 
1
 
+
_____
 
 
3
 
 
4.
2
 
 
_____
 
 
9
 
 
1
 
+
_____
 
3
 
 
5.
3
 
 
_____
 
 
10
 
 
1
 
+
_____
 
 
5
 
 
6.
2
 
 
_____
 
 
5
 
 
1
 
+
_____
 
 
3
 
 
         
7.
2
 
 
_____
 
 
7
 
 
1
 
+
_____
 
 
3
 
 
8.
2
 
 
_____
 
 
8
 
 
1
 
+
_____
 
 
4
 
 
9.
2
 
 
_____
 
 
5
 
 
2
 
+
_____
 
 
4
 
 
10.
3
 
 
_____
 
 
6
 
 
1
 
+
_____
 
 
4
 
 
11.
1
 
 
_____
 
 
6
 
 
1
 
+
_____
 
 
3
 
 
12.
1
 
 
_____
 
 
2
 
 
1
 
+
_____
 
 
6
 
 
           
13.
1
 
 
_____
 
 
3
 
4
 
+
_____
 
 
12
 
 
14.
3
 
 
_____
 
 
9
 
 
1
 
+
_____
 
 
3
 
 
15.
2
 
 
_____
 
 
6
 
 
2
 
+
_____
 
 
5
 
 
16.
4
 
 
_____
 
 
8
 
 
2
 
+
_____
 
 
4
 
 
17.
1
 
 
_____
 
 
3
 
 
4
 
+
_____
 
 
9
 
 
18.
2
 
 
_____
 
 
7
 
 
5
 
+
_____
 
 
14