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March 31st, 2019, 10:45 AM  #1 
Newbie Joined: Mar 2019 From: N.Ireland Posts: 5 Thanks: 0  Impossible thought
3 x 4 = 12... 7 x 8 = 56... Nb the sequence of digits... Is there any other combination of consecutive digits that produce an answer which itself is made up from consecutive digits... In these examples the answer is also the immediate precursors to the sequence of the multipliers ...coincidence?? Of course .... Is there a simple proof showing these are the only numbers ? 
March 31st, 2019, 11:03 AM  #2 
Senior Member Joined: Aug 2012 Posts: 2,343 Thanks: 732 
9 x 10 = 90.

March 31st, 2019, 11:05 AM  #3 
Newbie Joined: Mar 2019 From: N.Ireland Posts: 5 Thanks: 0 
Vg... Nicely done... With some poetic licence 
March 31st, 2019, 11:51 AM  #4 
Newbie Joined: Mar 2019 From: N.Ireland Posts: 5 Thanks: 0 
Doh.... Forgot to say excluding 1 x ( n, n+ 1,n+2 ,n+3 ....... )
Last edited by Paulb; March 31st, 2019 at 12:22 PM. 
March 31st, 2019, 12:20 PM  #5 
Global Moderator Joined: Dec 2006 Posts: 20,835 Thanks: 2162 
78 × 79 = 6162

March 31st, 2019, 12:23 PM  #6 
Newbie Joined: Mar 2019 From: N.Ireland Posts: 5 Thanks: 0 
Yes many answers with nice figures but not sequential...

March 31st, 2019, 12:49 PM  #7 
Global Moderator Joined: Dec 2006 Posts: 20,835 Thanks: 2162 
Poetic licence allows me to use a number base of 100 instead of 10. As you didn't require the consecutive digits to be in ascending order, 7 × 6 × 5 = 210. 
March 31st, 2019, 12:55 PM  #8 
Newbie Joined: Mar 2019 From: N.Ireland Posts: 5 Thanks: 0 
Brilliant...... 

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