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PYHIYP #1 (Posted on 2019-12-09) Difficulty: 2 of 5
PYHIYP means: Put your hands in your pockets i.e. use no calculators, no pen & paper; just your eyes and you brain.

The 1st task, a harbinger to be followed by many others, is to prove just by observation and common sense that none of the four numbers listed below is a prime.

i. 5,234,567,896,743
ii. 1,438,525,775,258,341
iii. 77,112,356,378,491
iv. 1,431,436,216,211,339

No time limit!
No cheating!
KISS!
Post your conclusions.

No Solution Yet Submitted by Ady TZIDON    
Rating: 4.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Answers | Comment 5 of 8 |
The third one is comprised of bits that are clearly divisible by 7
77/7=11
112/7=(2*49+14)/7=16
35/7=5
63/7=9
7/7=1
84/7=12
91/7=13
77112356378491=7*11016050911213

(In response to Steve Herman:  I didn't think to check for divisibility by 3.  It seemed too obvious.)

  Posted by ellieleigh on 2021-01-29 01:42:50
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