Last winter I found myself locked out of my house because I couldn’t remember the 5-digit code to open the garage door. I used the following facts to get inside.
1. The second and third digits add up to 9. 2. The first digit is equal to the second digit cubed. 3. The sum of the third and fifth digits is the smallest number with exactly five divisors. 4. The fourth digit is equal to 6 times the second-to-last digit. 5. None of the digits repeat.
If we label each digit a, b, c, d and e, we get the following equations. 1. b + c = 9 2. a = b3 3. c + e = 16 (since 16 is the smallest number with five divisors – 1, 2, 4, 8 and 16). 4. d = 6 * d (The fourth and second-to-last digits are the same number, meaning d must be zero to satisfy the equation) 5. b must be zero, one or two (b can’t be three because that makes a=27, which isn’t a single digit). Zero and one result in duplicate digits (00907 and 11808 respectively) so the only remaining value for b is 2, giving us 82709 and warmth.
Mario is testing out a new car at the racetrack. His grandmother took it for a mile lap and averaged 30mph. How fast does Mario have to drive in the second lap to average 60mph for the two miles?
90mph is an alluring answer, but it’s impossible. At 90mph the second lap would take 40 seconds. If Grannie’s first lap at 30mph took 2 minutes, traveling 2 miles in 2 minutes and 40 seconds is an average speed of 45mph. Traveling an average speed of 60mph for 2 miles would take 2 minutes and since the grandma’s lap took all of those 2 minutes, even if Mario could break the sound barrier he wouldn’t be able to average 60mph.
Because Oct 31 represents the octal (base 8) number 31, which, when converted to decimal, is 25. Dec 25 is short for Decimal 25, thus the two are equal.
Daughter-in-law. Her daughter’s father is her husband (she’s only been married once and is devoted, meaning she didn’t have an affair). This means John’s son is her husband, so John is her father-in-law, making her the daughter-in-law.
Early one morning Hal, the owner of a hardware store, sells a mailbox for $25 to Courtney that cost him $20 wholesale. Courtney pays with a $100 bill and Hal discovers he doesn’t have enough change. He runs to the jewelry shop next door, where Jack, the owner, gives him change in exchange for the $100. Later that afternoon, Jack discovers the $100 bill is a counterfeit and Hal pays him $100 to make it right.
The total loss was $95. -$20 = The wholesale cost of the mailbox $100 = The money from Jack -$75 = The change paid to Courtney -$100 = To pay Jack back -$20 + $100 – $75 – $100 = -$95
It’s easy to think Hal lost $195 but that fails to account for the $100 used to make the change, which came from Jack, not Hal. Jack paid $100 in exchange for a worthless piece of paper, so the $100 was initially Jack’s loss. Hal had made a $5 profit until Jack’s discovery. If you guessed $100, that’s arguably correct, but not making $5 in profit isn’t a loss in the strictest sense of the word.
Sequoia, eulogia or miaoued are all good options, but there’s an even shorter (and more obscure) word with all the vowels and not a single consonant: Iouea. It’s not the kind of word you’d use at the dinner table, but it’s listed in the Wikipedia dictionary as a genus of Cretaceous fossil sponges.
If you got really tricky and tried to find a word that contained the letters in the phrase ‘all of the vowels’, you probably found, like I did, that there isn’t one. But it was still worth checking.
You watch a group of words going to a party. A word either enters through one of two doors or is turned away by the guards. ‘HIM’ goes through door number one and ‘BUG’ goes through door number two. ‘HER’ is turned away. ‘MINT’ and ‘WEAVE’ go in through door one, ‘DOOR’ and ‘CORD’ take door two and ‘THIS’ and ‘That’ aren’t allowed in.
What determines whether a word can enter and which door they must use?
Door number one is for words composed entirely of capital letters written using only straight lines, such as A, E, F, H, and I. The entire set of letters allowed through door number one are AEFHIKLMNTVWXYZ. Door number two, as might be expected, is for words with capital letters that have a curve, including BCDGJOPQRSU. Any words composed of both straight and curved letters (or lowercase letters) are not allowed in. The word ‘THAT’ would have been sent through door number one, if the letters had been capitalized.
A couple has two children. At least one of them is a boy. Assuming the probability of having a boy or girl is 50%, what is the probability that both children are boys?
If you answered 1/2, you’re not without comrades, but the generally accepted answer by statisticians (though not without debate) is 1/3. This is because there are four possible combinations: boy-boy, boy-girl, girl-boy and girl-girl. Since we are told one of the children is a boy (but we don’t know if it’s the first or second child), we can rule out the girl-girl combination, leaving three remaining options. Only one out of 3 is boy-boy, so we get a 1/3 chance.