# What is the sixth number?

It is said that designers take 10 seconds to resolve this, engineers take 3 minutes, architects 3 hours and doctors 6 hours.

You have to guess what the 6th number is.

1, 2, 6, 42, 1806, ___???

3263442

Scroll down for why

1x1+1=2

2x2+2=6

6x6+6=42

42x42+42=1806

1806x1806+1806= 3263442

 DifficultyModerate TypeMathematical

3,263,442(1806+1807)
- (30 Apr 2009)

2 X 3=6
6 X 7=42
42 X 43=1806
1806 X 1807 = 3,263,442
- (2 May 2009)

1 x 1 = 1, 1 + 1 =2
2 x 2 = 4, 4 + 2 = 6
6 x 6 = 36, 36 + 6 = 42
42 x 42 = 1764, 1764 + 42 = 1806
1806 x 1806 = 3261636, 3261636 + 1806 = 3263442
- (4 Jun 2009)

i took about 2 -3 mins.im not a designer or engineer.
but i think it is 3263542
- Dena (14 Jun 2009)

the next number can be found like this- n^2 + n
- Casey (30 Oct 2009)

This took me 30 seconds
- Nick (10 Nov 2009)

very true!! bein an engineer i solved it within 3 mins.. :)
- Amretha (9 Dec 2009)

i'm in high school and i got it in about 30sec
- Awesome (7 Mar 2010)

1 x 2 = 2
2 x 3 = 6
6 x 7 = 42
42 X 43 = 1806
1806 x 1807 = 3263442
- Chris (9 Mar 2010)

that ws nt true bcs i am a doctor and i took just 10seconds

another method is
n*n+1
1*1+1=2
2*2+1=6 and so on
- seena (13 Jun 2010)

I'm an unemployed stoner and I solved this in 45 secs. (I must confess I used a calculator though)
- herbie (16 Mar 2011)

hah 15 seconds

- Kellie (22 Jul 2011)

I am an engineer & took less than 3 min.. but how do u say a designer will take 10 sec?
- Sathish (15 May 2012)