long multiplication slidecast
DESCRIPTION
TRANSCRIPT
Long Multiplication
By Mr. Kish
Pros and Cons
Pros
• Likely faster than partial products
• Works everytime• Better understood by
most people (e.g. parents)
Cons
• It isn’t clear why it works
• Some steps can be forgotten
• Some students have a hard time mastering
An example of long multiplication
x
6 35 4
An example of long multiplication
x
Make an estimate
6 35 4
An example of long multiplication
x
Make an estimate
60 * 50
6 35 4
An example of long multiplication
x
Make an estimate
60 * 50 = 3,000
6 35 4
An example of long multiplication
x
6 35 4
An example of long multiplication
x
2
6 35 4
An example of long multiplication
x
2
1
6 35 4
An example of long multiplication
x
252
1
6 35 4
An example of long multiplication
x
252
1
0
6 35 4
An example of long multiplication
x
252
1
50
1
6 35 4
An example of long multiplication
x
252
1
3150
1
6 35 4
252
An example of long multiplication
x
1
3150
1
+
6 35 4
252
An example of long multiplication
x
1
3150
1
+
3042
6 35 4
An example of long multiplication
x
Make an estimate
9 16 2
An example of long multiplication
x
Make an estimate
90 * 60
9 16 2
An example of long multiplication
x
Make an estimate
90 * 60 = 5,400
9 16 2
An example of long multiplication
x
2
9 16 2
An example of long multiplication
x
182
9 16 2
An example of long multiplication
x
1820
9 16 2
An example of long multiplication
x
18260
9 16 2
An example of long multiplication
x
1825460
9 16 2
182
An example of long multiplication
x
5460+
9 16 2
5642
182
An example of long multiplication
x
5460+
9 16 2
A more complex example
6 2 4x 3 3 1
A more complex example
6 2 4x
6213 3 1
18720187200+
206,544