Early Multiplication Methods

1
Early Multiplication Methods

• Section 4.5

2
Duplation and Mediation

• Duplation Double a number
• Mediation Halve a number

3
Duplation and Mediation

• Mediate on the left, Duplate on the right.
• When mediating, leave off any remainder.

4
21 x 32

• 21 32

5
21 x 32

• 21 32
• 10 64

6
21 x 32

• 21 32
• 10 64
• 5 128

7
21 x 32

• 21 32
• 10 64
• 5 128
• 2 256

8
21 x 32

• 21 32
• 10 64
• 5 128
• 2 256
• 1 512

9
Cross off all rows with even numbers in the
left-hand column

• 21 32
• 10 64
• 5 128
• 2 256
• 1 512

10
Add the remaining numbers in the right-hand
column for answer

• 21 32
• 10 64
• 5 128
• 2 256
• 1 512
• 672

11
Lattice Multiplication

• Lattice Grid.
• Place the numbers to be multiplied outside the
  lattice.
• Fill in each box in the lattice by multiplying
  the numbers outside the lattice.
• Add across the diagonals for answer

12
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13
43 x 92
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3 x 9 27
15
4 x 9 36
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3 x 2 6 06
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4 x 2 8 08
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6 6
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7 0 8 15. Write 5, carry 1
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1 2 6 0 9
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3 3
22
Read along outside, starting at 3, for answer
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Answer is on the outside