Multiplication Doubling and Halving Strategy
When multiplying two numbers, if one of the numbers is an even number, the "Doubling and Halving" method can simplify the calculation.
Steps:
Halve the even number: Take the even number and divide it by two. At the same time, double the other number.
Repeat the process: Continue applying this method until the multiplication becomes straightforward or easy to compute.
Find 90 × 16
Start by applying the Doubling and Halving method:
90 × 16
= Double 90 and Halve 16
= 180 × 8
= Double 180 and Halve 8
= 360 × 4
= Double 360 and Halve 4
= 720 × 2
= Double 720 and Halve 2
= 1440 × 1
The result is:
1440
Find 125 × 84
Apply the Doubling and Halving method:
125 × 84
= Double 125 and Halve 84
= 250 × 42
= Double 250 and Halve 42
= 500 × 21
= Multiply directly: 500 × 21 = 10500
The result is: 10500
Find 143 × 16
Apply the Doubling and Halving method:
143 × 16
= Double 143 and Halve 16
= 286 × 8
= Double 286 and Halve 8
= 572 × 4
= Double 572 and Halve 4
= 1144 × 2
= Double 1144 and Halve 2
= 2288 × 1
The result is: 2288
Find 200 × 0.32
Apply the Doubling and Halving method:
200 × 0.32
= Double 200 and Halve 0.32
= 400 × 0.16
= Double 400 and Halve 0.16
= 800 × 0.08
= Double 800 and Halve 0.08
= 1600 × 0.04
= Multiply directly: 1600 × 0.04 = 64
The result is: 64
