Problem-solving Solution- Work backwards

	Problem Solving Strategy ~ Work Backwards ~

Solution

1.Make a table and work backward from year 7 when there are 3200 rabbits. Since population doubles each year, working backward means halving it.

Year	No. of Rabbots
7	3200
6	1600
5	800
4	400
3	200
2	100
1	50

There were 50 rabbits in year one.

2. Work backward from each of 3 friend having 2 apples.

Forward Step	Backward Step
Each of 3 friends has 2 apples	Total : 3 x 2 = 6 apples
I kept half of them for myself	Total : 6 x 2 = 12 apples

I bought 12 apples.

3. Start with the end result 20.

Forward Step	Backward Step	Working
Final Result	20	20
Multiplt by 2	Divide by 2	20 / 2 = 10
Subtract 6	Add 6	10 + 6 = 16
Add 12	Subtract 12	16 - 12 = 4

The starting number is 4.

4. Reverse the steps

Forward Step	Backward Step	Working
?	?	63
\| v	^ \|	^ \|
Divide by 7	Multiply by 7	9 x 7 = 63
\| v	^ \|	^ \|
Multiply by 2	Divide by 2	18 / 2 = 9
\| v	^ \|	^ \|
Add 2	Subtract 2	20 - 2 = 18
\| v	^ \|	^ \|
20	20	20