+1

18*1= 18 and since 9 months is 75% of a year I calculated 75% of 18 that to get the result.

 

Well...this is 6 grade math (arithmetics) here.

And yes it is normal, and no you are not a freak nor a genius. NORMAL is the key word here. But also i know a guy that does this straight on and gives the result just as quick if not quicker. He does also square roots of bigger numbers and also come up with prime numbers up to 4 digits.

So trust me, what you're doing is normal.

 

you guys are funny. that is the most common way to do math. +1 to the above. this is what you were taught as a child. you told your math teacher you would never use what he taught you in real life. you were wrong. i just saw the wind taken out of a lot of genius sails.


from about.com:

What is the Distributive Property in Arithmetic and Algebra?

Named the 'Distributive Property (sometimes referred to as the distributive law) because in essence, you are distributing something as you separate or break it into parts. The distributive property makes numbers easier to work with. In algebra when we use the distributive property, we're expanding (distributing).

The Distributive Property in Arithmetic:

The Distributive Property lets you multiply a sum by multiplying each addend separately and then add the products. The Distributive Property helps with mental math and should be taught to children as a method to multiply much quicker in their heads. Children need lots of experience using the Distributive Property. Children make greater 'connections' with the ability to use the distributive propertly for mental math. For instance:

Let's say I have to quickly multiply:

4 x 53
(4 x 50) + (4 x 3)
200 + 12
212

In my mind, I can compute the answer of 4x50 quickly (200) then I add (4x3) 12 to give me 212. That's why using the Distributive property can come in handy!

Let's try another:

12x19 - Well 12 x 20 is easy, it's 240 But, I added one more 12 than I needed, so I'll take it away from 240 to give me 228.

One more!

4 x 27
=4(20 +7)
=4(20) + (7)
=80 + 28
=108

Students should have lots of opportunity to break numbers apart using the distributive property which greatly assists the mental math process.

 

if anyone still thinks they are a genious, take advantage of this. It is a great opportunity to be a part of an elite mental group. Only the top 2% intelligent humans on this planet are allowed to join.

http://www.mensa.org/contact.php?action=show

 

I don't think anyone on the thread thinks they're a genius, the word was never mentioned. I just wanted to know if the way I work things out is normal because everyone in the room I was with said they didn't do it the way I did. So I just wanted a wider audience. It certainly wasn't the way I was taught in school. I always preferred my own methods, but when it came to taking exams I had to show that I could do it the lame way too.

Purely coincidentally though, I did take the sit-down supervised mensa test and was invited to join with a score of 148. I assume that's the actual IQ figure but I can't be sure, it was quite a few years back. It seemed like it would be just a waste of however much they wanted to keep membership going and to get to hang out with a bunch of geeks (not that I'm saying I'm not one ).

 

i was trying to funny more then anything else . your way of working it out is pretty normal of a functional adult.

i considered taking the test, my roommate in savannah did. he paid like 40 bucks a year and got a newsletter he never read and invitations to meetings with a bunch of nerds. he never went. maybe you can put it on a resume? i know in my field that would be a positive thing to list.

 

Just for grins, I took the sample test. I got 24 of 30 in about 15 minutes of effort.

 

Nice comeback!
Take that Craigmeister!

(Pretty sure I couldn't buy my way in.... )

 

To answer the problem I first decided to determine how many years she was NOT pregnant.
3 mos of every year she is not pregnant x 18 = 54. (54mos = 4.5 yrs) 18 minus 4.5 = 13.5

 

If that's what worked for you then great, but to me it feels like the long way around.