Winco
Diamond Member
- Nov 1, 2019
- 29,203
- 20,506
- 2,290
So when a student raises their hand and offers this solution (below) are you thinking this is an awesome example of thinking outside the box or are you thinking, just do it the traditional way.Mississippi's schools test scores soared after reinstituting phonics. And yes, I very much would use standard old school multiplication process. Results are what matters.
Student Response.
Since 100 x 100 =10,000
Then 96 x 104 would be 16 less than 10,000.
I can subtract 16 from 10,000 faster than using traditional math.
The answer of 9,984 is 16 less because each number is 4 away from 100.
Since I know binomial expansion of conjugates, I can apply this rule.
Therefore 95 x 105 is 25 less than 10,000 or
95 x 105=9,975
Would you accept this ^^^^^ students answer?