Solve the Mystery: What is 9 times 7?

  • Context: High School 
  • Thread starter Thread starter bbg5000
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around a riddle-like question regarding the multiplication of 9 and 7, with participants exploring a pattern in calculations that deviates from standard multiplication. The scope includes mathematical reasoning and conceptual exploration.

Discussion Character

  • Exploratory, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant presents a series of calculations that suggest a pattern in how multiplication results are derived, leading to the question of what 9 times 7 would yield.
  • Another participant proposes a method of normal multiplication followed by taking the difference between the digits of the result, applying this to the previous examples to arrive at a conclusion for 9 times 7.
  • A third participant expresses surprise at the proposed method, indicating a lack of familiarity with it.
  • A later reply dismisses the initial premise as "utter nonsense," suggesting disagreement with the approach taken in the riddle.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, with some supporting the proposed method of calculation while others challenge its validity.

Contextual Notes

The discussion includes assumptions about the validity of the riddle's premise and the proposed mathematical approach, which remain unresolved.

bbg5000
Messages
14
Reaction score
0
It's like a riddle thinger..

If 9 times 9 is 7
10 times 9 is 9
10 times 8 is 8
8 time 8 is 2

What is 9 times 7 ?

It says to "Think mathematically. There is a pattern of calculating involved."

Anybody got any idea what this is? What the answer is??
 
Physics news on Phys.org
Multiply the numbers (using "normal" multiplication), then take the difference between the digits.

9 * 9 = 81 and 8 - 1 = 7.
10 * 9 = 90 and 9 - 0 = 9.
10 * 8 = 80 and 8 - 0 = 8.
8 * 8 = 64 and 6 - 4 = 2.

Since 9 * 7 = 63, the answer you're looking for is probably 6 - 3 = 3.
 
Wow.. I never saw that. Thanx
 
Originally posted by bbg5000
It says to "Think mathematically...

Utter nonsense.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 23 ·
Replies
23
Views
27K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 33 ·
2
Replies
33
Views
3K