I was just watching a local adoption of the show "Are you smarter than a 5thgrader?" and there was an old lady playing. She struggled to answer a question "Find a way to express 10 with five 9". While she figured out 99/ 9 - 9/9 = 10, I figured out 14 more ways to do it?

How many ways can you guys find?

P.s. I used derivatives, trigonometry, logarithms. There definitely are more ways, but the number I gave is how many I found during the question.

Originally posted by kbaumen I was just watching a local adoption of the show "Are you smarter than a 5thgrader?" and there was an old lady playing. She struggled to answer a question "Find a way to express 10 with five 9". While she figured out (99 - 9) - 9/9 = 10, I figured out 14 more ways to do it?

How many ways can you guys find?

P.s. I used derivatives, trigonometry, logarit ...[text shortened]... ere definitely are more ways, but the number I gave is how many I found during the question.

the old lady lost didn't she?
Because she found a way to express 89 inted of 10:
(99-9)-9/9=90-1=89 !!!
here's a easy one : 99/99 + 9

Originally posted by alexdino the old lady lost didn't she?
Because she found a way to express 89 inted of 10:
(99-9)-9/9=90-1=89 !!!
here's a easy one : 99/99 + 9

sin9sin9 + cos9cos9 + 9 = 10
(99 - 9)/9 + derivative(9) = 10 (I suppose if you derive a constant function, hence a constant number, the derivative is 0)
(tg9ctg9 + 9) * 9 / 9 = 10

Eh, yeah, there really are tons of possibilities.

Ok, let's make 1 to 100 with five 9. (with only + - * /, hence no trigonometry, logarithmic expressions, calculus, combinatorics and other creepy stuff)

EDIT: Damn, I didn't mention square root. Ah, consider it an option. I think some numbers will be quite hard to get without sqrt. However, no sqr(9), hence 9^2, please.

6 = (9/9)^9 * (9 - sqrt(9))
numbers not so close to multiples of 9 are a bit more dificult so i thinc that without sqrt you can't get them wiith only 5 9s.
but you can always try!
7 = 9 - 9/9- 9/9