Welcome to Carsten's Test - Can You Solve the Equation?

[arcnets]

Hi, I'm the guy formerly known as carsten. This is just a test to see if everything works.
OK, you have the numbers
1 2 3 4 5 6 7 8 9 0.
You may insert some + signs and one = sign so to make a valid equation.
Like
12+34+5+6+78=90 (oops, false! )

Happy posting, and a big thanks to Greg who does a great job IMO.

 

[Mulder]

Easy ..
1+2+3+4+5+67+8=90

 

[arcnets]

Yes. There's more solutions.

 

[drag]

1 + 2 + 3 + 4 + 56 + 7 + 8 + 9 = 90
12 + 3 + 45 + 6 + 7 + 8 + 9 = 90

 

[Njorl]

You used the 9's twice drag.

12+3+4+56+7+8=90
1+23+45+6+7+8=90
nothing =890
nothing=7890
etc.

Njorl

 

[Njorl]

If 2ⁿ-1 is prime, what can you say about (2ⁿ-1)*(2^n-1)?

Njorl

 

[Ben-CS]

Perfect!

 

[Njorl]

Absolutely. I thought that would take longer.

Njorl

 

[climbhi]

Originally posted by Ben-CS
Perfect!

What do you mean perfect?

 

[Njorl]

A perfect number is equal to the sum of its factors. For this purpose, 1 is considered a factor, but the number itself is not.

Factors of 6 are 1,2,3 1+2+3=6
Factors of 28 are 1,2,4,7,14 1+2+4+7+14=28

6 and 28 are perfect.

Njorl