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Friday, 25 October 2013

Prime pyramid-Adjacent primes

You are to work out a number pyramid starting with 1 number in the first row,2 in the second,3 in the third,4 in the fourth row and so on.Each row should start with digit 1 and end with the digit represented by the row,for example the 7th row should end with 7.The digits/numbers to be filled up in between should be such that each pair of adjacent numbers should sum up to a prime.A few rows are shown filled up below-
1-                       Sums involved  -nil
1,2                                             3
1,2,3                                          3,5
1,2,3,4                                       3,5,7
1,4,3,2,5                                    5,7,5,7
1,4,3,2,5,6                                 5,7,5,7,11
1,4,3,2,5,6,7                              5,7,5,7,11,13
1,6,7,4,3,2,5,8                           7,13,11,7,5,7,13
Try filling up subsequent rows.There could sometimes be more ways in respect the digits/numbers involved in the middle of each row.
It may not be easy when you proceed upto row 17,19 etc.


Wednesday, 23 October 2013

Surprise in sudoku-rejoinder

Were you able to fill up the sudoku grid shown by me?
The completed grid will be as shown below-(row-wise)
418 239 657
695 781 342
273 546 819
961 853 274
354 627 981
782 914 563
546 192 738
839 475 126
127 368 495
I have deliberately shown the digits in groups of three
There is a  surprise in rows 1,3,5,7 and 9 where you will notice an addition sum as follows-
418+239=657
273+546=819
354+627=981
546+192=738
127+368=495 

Wednesday, 16 October 2013

Probability for division of one number by another

Choose any number (A)between 10 and 1000.Remove the last digit in the same to get another number (B).For example if A is 456 ,B will be 45.What is the probability that A will be divisible by B?

Tuesday, 15 October 2013

A sudoku with a surprise

Here is the grid for filling up by you-should not be difficult-The cells which were left blank have been marked b-
bbbbb96bb
6b5b8bbb2
bbbb4bbb9
b6185bb7b
b5bbbbb8b
b8bb1456b
5bbb9bbbb
8bbb7b1b6
bb73bbbbb
Fill it up and find out what the surprise is. I cannot reveal it now as you will be able to fill up the grid more easily.