Brain Teasers 15-7.5

1.  What’s a good method to solve this problem mentally?   (2015 + 2015) x 50  (Note:  “good” is subjective, and there could be more than one right answer, but your solution will need words.  The ‘answer’ to the problem itself is not the issue. :-))
2.  Next year (2016) is a leap year.  On what date next year will 2/3 of the year have elapsed?
3.  Use these clues to figure out the year the first US transcontinental railroad was completed:

a.  The sum of the digits is 24.

b.  The ones and the tens digits are multiples of 3.

c.  The hundreds digit is 1 less than the ones digit.

4.  The centers of fence posts are 30 inches apart.  They enclose a triangular region 20 ft x 20 ft x 10 ft.  How many posts will be needed?
Held over from last week:
5.  If the digit 7 is written at the right of a certain number, that number is increased by 70,000.  Find the number.
6.  How many whole numbers are between the square roots of 8 & 80?
7.  The number 6, say, has 4 whole-number divisors: 1,2,3,and 6.  What is the smallest number with exactly FIVE whole-number divisors?
8.  Take a person with a pulse rate of 72 beats/minute.  How many times will his/her heart beat in April?


Submit Answers!  There are NO tests and the answers are NOT graded, so lighten up!  🙂  If you want to submit  your answers to any or all of these, please do so!!  
You can always do this 3 ways:  1)  Use the Leave A Reply section below (though I may not make it public until after the deadline);   2) reply to (or contact) me directly by e-mail or by replying to any Weekly Sharing; or 3) by using the Contact Form link.   Your anonymity is protected for all formats (but only until submission deadline for the Leave a Reply format. )
Reminder:  Deadline for submissions (at least for recognition next week) is noon on Thursday 4/16.  

One thought on “Brain Teasers 15-7.5

  1. Your picture of the week (which is very nice, by the way) reminded me of an old joke. This guy goes into a 2-holer in the Ozarks, one of which is occupied. So, he sits down to do his business. The other guy finishes and begins pulling up his bib overalls. All of a sudden, several coins slip out of his pants pockets and go down into the hole he has just vacated. Without saying a word, the man pulls out his billfold, removes a $20 bill, and throws it down the hole after the coins. Astonished, the man still seated asks, “Why on earth did you just throw a $20 bill down that hole?” The first man responds, “You don’t think I’m gonna crawl down in there for 75 cents, do you?”
    Now THERE is a solution to a [sort of] math problem.

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