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No. 2 Strange Maths
You have come across a set of strange mathematical equations that seem to defy normal logic. One of the equations remains unsolved. For this brainteaser establish the solution to the unsolved equation and explain how it was solved. |
| 15 + 7 =
24 23 -13 = 10 11 * 22 = 242 |
| 142 / 7 = ?? |
The solution was of course |
| 15 + 7 =
24 23 -13 = 10 11 * 22 = 242 |
| 142 / 7 = 16 |
The mathematical expressions were all in base 8 (octal) notation instead of the base 10 (decimal) we are most used to seeing. |
Congratulations go to "Jonas Minnberg" for sending in the first correct answer. The following section contains every correct answer in the order it was received. Thank you all for taking part. |
From: Jonas Minnberg
Subject: answer
Its in octal, the answer is 16
Jonas Minnberg (Sasq)
From: Eric Welser
Subject: no. 2: strange maths
These equations were done in base-8
so, 142/7 = 16
Eric Welser
From: Aggravated Nosebleed
Subject: puzzle 2
16
From: Mat Noguchi
Subject: Answer to 2
The numbers are in base 8.
(Equations rewritten in base 10)
13 + 7 = 20 = 2*8 + 4
19 - 11= 8 = 1*8 + 0
9*18 = 162 = 2*64 + 4*8 + 2
So
142/7 in base 8 is
(1*64 + 4*8 + 2)/7 = 98/7 = 14
or in base 8:
16
From: Richard Bradley
Subject: No. 2 Strange Maths
All of the equations are using octal numbers. So 142/7 = 16 (14 decimal) when using a base 8 number system.
From: Brandon Fliflet
Subject: BrainTeaser #2
Answer is 16 in base 8 that is. :-)
Brandon Fliflet
Sr. Software Engineer
Intel Corp.
From: Kurt Miller
Subject: brain teaser 2
Its not base 10 as most would assume... its octal. The answer is 16.
Kurt Miller
From: Theiet
Subject: Answer to brain teaser
16
Its in base8
From: Chris Thompson
Subject: octal
16
it's octal
Chris 'Lightman' Thompson
From: Paul-Jan Pauptit
Subject: Brainteaser # 2 (answer = 16)
The calculations are in a base-8 (octal) system instead of
the ordinary
base-10 (decimal) system.
So the correct answer to the remaining equation would be 16.
p.s. I !hate! octal calculations! Next time please do binary or hexadecimal ;-)
Paul-Jan Pauptit (aka The Watcher^TUHB)
From: Frederic Lopez
Subject: Brain Teaser no. 2
Hi,
don't know if it's too late to give an answer, but here it
is :
the equations use octal numbers. The solution is 16 in octal
(which is 98/7=14 in decimal).
From: BILL ADAMS
Subject: Solution to No. 2
The answer is 16. All calculations are in octal format.
From: Pierre Maloka
Subject: Teaser #2
Octal Math.
Answer is 16.
From: RSte
Subject: Brainteaser n. 2
The set of equations is solved using base 8 so
142 / 7 = 16
Note: 11*22=242 and 23-13=10 in any base (funny!), but 15+7=24 only in base 8.
Ciao!
From: Jamie
Subject: Solution 2
The mathematics is being done in base 8 instead of base 10.
For this reason, 142 / 7 = 16
Jamie Love
From: Marek Rabas
Subject: No. 2 Strange Maths
"The equation uses octal enumeration" Answer: 16
Marek Rabas
Programmer
Ward Six Entertainment, Inc.
From: Iain Davies
Subject: Brainteaser #2
Answer: 16
The numbers are in base 8
15(base8) + 7(base8) = 24(base8) => 13 + 7 = 20
23(base8) - 13(base8) = 10(base8) => 19 - 11 = 8
11(base8) * 22(base8) = 242(base8) => 9 * 18 = 162
142(base8) / 7(base8) = 16(base8) => 98 / 7 = 14
The missing number is 16(base8)
From: Peter Hall
Subject: No. 2 Strange Maths
The solution to the unsolved equation is 16, because the mathematical equations are using base 8 (or octal), in which 15+7 is still 24, but 23-13 is still 10, and 11*22 is still 242.
From: Alex Clarke
Subject: Solution.
In base 10, the equations are nonsense, but in base 8 they make perfect sense.
So
142 / 7 = 16
Since the windows calculator can work in octal, this is easy to prove for yourself.
Alex Clarke
Speaking only for myself.
From: BRIAN MAKUCH
Subject: Brianteaser: No. 2 Strange Maths
142 / 7 = 16
The equations use a base 8 (octal) numbering system.
