A number of 50 digits has all its digits equal to 1 except the 26th digit. If the number is divisible by 13, then find the digit in the 26th place.
doubt this will help but the sum of the digits of multiples of thirteen (and the sum of those digits if their 2 digit numbers) goes in a patern:
4,8,3,7,2,4,1,5,9. Therefore, sice 3 and 6 arent present in the patern, we can rule out 2 and 8.
49*1+2=51. 5+1=6.
49*1+8=57. 5+7=12. 1+2=3.
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Posted by rerun141
on 2003-11-15 11:06:34 |
first thoughts
