Can you find the pattern?

[Blackops]

I tried a lot but no luck to see what's going on here. Can you find any pattern?

11*13=12
13*16=33
15*17=28
16*20=36
21*25=40
23*24=??

 

[Dr.Peterson]

I don't see it yet, but I see that the output is always divisible by the difference of the inputs.

 

[topsquark]

I tried a lot but no luck to see what's going on here. Can you find any pattern?

11*13=12
13*16=33
15*17=28
16*20=36
21*25=40
23*24=??

23 * 24 "=" 11.

Dr.Peterson gave the clue. To get the number add the digits of both numbers, then multiply that by the difference between the two numbers.

For example, 13 * 16 = 33. --> Sum of digits = 1 + 3 + 1 + 6 = 11. Difference between the numbers 16 - 13 = 3. So 11 * 13 "=" 3 *11 = 33.

-Dan

 

[Deleted member 4993]

23 * 24 "=" 11.

Dr.Peterson gave the clue. To get the number add the digits of both numbers, then multiply that by the difference between the two numbers.

For example, 13 * 16 = 33. --> Sum of digits = 1 + 3 + 1 + 6 = 11. Difference between the numbers 16 - 13 = 3. So 11 * 13 "=" 3 *11 = 33.

-Dan

How in the heck did you figure that out ?!

 

[Blackops]

Thanks guys. You are GREAT.

 

[topsquark]

How in the heck did you figure that out ?!

I'm just that d*mned good.

There is someone (I have forgotten the member name) on a couple of the other forums and he gave a problem whose solution dealt with the sum of the digits. I thought I'd give it a try.


-Dan

 

[Dr.Peterson]

What I generally do for these (and didn't only because I was already late for lunch) is to add a column to the table for any function of the inputs that looks possibly relevant, and then look for connections from that to the output:

input x*y	output z	y-x	z/(y-x)
11*13	12	2	6
13*16	33	3	11
15*17	28	2	14
16*20	36	4	9
21*25	40	4	10
23*24	??	1

I'd just stare at the first and fourth columns looking for a connection. I see that the latter is bigger when there are big digits in the former (not when the former are larger numbers), and that might lead me to look at something like the sum of digits. Then I write those in the last column and realize I have it.

Or I might give up instead ...