Lattice Multiplication with Decimals

1
Lattice Multiplicationwith Decimals

• Step-by-Step

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3.42 6.9
Ok! I know how to do Lattice, but I dont
remember how to multiply with decimals!!!
3
3.42 6.9
Make a grid the exact size of your problem. A 2
digit number times a 3 digit number gets a 2 x 3
grid. Draw a diagonal line in each box.
4
3
2
6
9
4
3.42 6.9
Place the decimal point above/beside the line in
the grid.
.
4
3
2
.
6
9
5
3.42 6.9
.
Multiply 6 2 and place the answer in the grid
where the lines meet.
4
3
2
1
6
.
2
9
6
3.42 6.9
.
Multiply 4 6 and place the answer in the grid
where the lines meet.
4
3
2
1
2
.
6
4
2
9
7
3.42 6.9
Multiply 3 6 and place the answer in the grid
where the lines meet. Use a zero as a place
holder.
.
4
3
2
1
2
1
.
6
4
2
8
9
8
3.42 6.9
.
Multiply 2 9 and place the answer in the grid
where the lines meet.
4
3
2
1
2
1
.
6
4
2
8
1
9
8
9
3.42 6.9
.
Multiply 4 9 and place the answer in the grid
where the lines meet.
4
3
2
1
2
1
.
6
4
2
8
1
3
9
8
6
10
3.42 6.9
.
Multiply 3 9 and place the answer in the grid
where the lines meet.
4
3
2
1
2
1
.
6
4
2
8
1
3
2
9
8
6
7
11
3.42 6.9
Now add the diagonals and place the answer below
the grid. Be sure to carry to the next diagonal
if you have a 2 digit answer.
.
4
3
2
1
2
1
.
6
4
2
8
1
3
2
9
8
6
7
8
12
3.42 6.9
Now add the diagonals and place the answer below
the grid. Be sure to carry to the next diagonal
if you have a 2 digit answer.
.
4
3
2
1
2
1
.
6
4
2
8
1
3
2
9
8
6
7
9
8
13
3.42 6.9
Now add the diagonals and place the answer below
the grid. Be sure to carry to the next diagonal
if you have a 2 digit answer.
.
4
3
2
1
2
1
1
.
6
4
2
8
1
3
2
9
8
6
7
9
5
8
14
3.42 6.9
Now add the diagonals and place the answer below
the grid. Be sure to carry to the next diagonal
if you have a 2 digit answer.
.
4
3
2
1
2
1
1
1
.
6
4
2
8
1
3
2
9
8
6
7
3
9
5
8
15
3.42 6.9
Now add the diagonals and place the answer below
the grid. Be sure to carry to the next diagonal
if you have a 2 digit answer.
.
4
3
2
1
2
1
1
1
2
.
6
4
2
8
1
3
2
9
8
6
7
3
9
5
8
16
3.42 6.9
Now you need to place the decimal. Follow the
lines until they meet.
.
4
3
2
1
2
1
1
1
2
.
6
4
2
8
1
3
2
9
8
6
7
3
9
5
8
17
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Now drop on the diagonal to place the decimal.
.
4
3
2
1
2
1
1
1
2
.
6
4
2
8
1
3
2
9
8
6
7
3
.
9
5
8
18
3.42 6.9
Your answer is 23.598!!
.
4
3
2
1
2
1
1
1
2
.
6
4
2
8
1
3
2
9
8
6
7
3
.
9
5
8
19
That is Soooo Cool!!! Thanks!
3.42 6.9
23.598