Largest Product

Using all the digits from 1 to 7, what two numbers have the largest product? For example, 1234 x 567 = 699678 but you can do much better than that.

742 x 6531 = 4,846,002.

A similar problem can be found in L.A. Graham’s Ingenious Mathematical Problems and Methods with a range of 1 to 9, but the principle remains the same – the numbers with the smallest difference produce the largest product. You start out with the highest two digits, 7 and 6, then attach 5 and 4, putting the smaller of the two digits with the larger number, giving you 74 and 65. The next two highest digits are 3 and 2, giving you 742 and 653. Finally, you add the 1 to the lower number. Page 80 has the details of that solution.

Posted in Brain Teasers

You’ll See Me When the Sun is High and Also Late at Night

You’ll see me when the sun is high and also late at night,
I’m in the songs of holidays, when the snow is white,

Kings and Queens and royalty, are all found in me,
I’m the largest of them all, with just one you see,

Step by step with pounding feet, I’m tribes of angry men,
I’m above your hands right now, for help or to go again,

You’ll use me in the kitchen, or add a little more,
I’ll be in the years to come, and the days of yore.

What am I?

Twelve (12).

Noon and midnight are both 12 o’clock and the Twelve Days of Christmas is a popular Christmas carol.

There are twelve face cards in a standard 52-card deck and twelve is the largest number with one syllable.

There are twelve steps in Alcoholics Anonymous, a troy pound is 12 ounces, there were 12 tribes of Israel and a popular movie was called, “Twelve Angry Men” (12 members of the jury). There are twelve function keys on your keyboard. F1 often shows a help screen and F5 reloads pages in your browser.

Many recipes measure items by the dozen, adding one more for a baker’s dozen. There are twelve months in a year.

It’s surprising how many times the number twelve shows up in our culture.

Posted in Riddles
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Word Pairs to Create a New Word

One letter can be used to replace the first letter of each word pair below to create two new English words. The new letters can then be combined to spell a word. What is that word?

MAIL ____ PINK
CART ____ SAID
GRID ____ RIMLESS
LINK ____ BOUND
ROWED ____ RIPPLE

SMART

SAIL – SINK
MART – MAID
ARID – AIMLESS
RINK – ROUND
TOWED – TIPPLE

Posted in Brain Teasers

Give Me Drink and I Die

Feed me and I live, give me drink and I die. What am I?

Fire.

Posted in Riddles

Five Items In a Tennis Court

We’re five little items of an everyday sort. You’ll find us all in a tennis court. What are we?

The vowels. The phrase “a tennis court” contains all five vowels sorted in alphabetic order: a, e, i, o, u.

Posted in Riddles

Number Abbreviations

What do these represent?

24 = HiaD
26 = LotA
7 = DotW
9 = LoaC
12 = SotZ
88 = PK

24 hours in a day
26 letters of the alphabet
7 days of the week
9 lives of a cat
12 signs of the Zodiac
88 piano keys

Posted in Brain Teasers

Eight Letter Word With KST

What eight letter word has kst inside, in the beginning, and at the end?

Inkstand.

The letters “kst” are in the word, “in” is at the beginning, with “and” at the end. I know, it’s awkwardly worded but otherwise it wouldn’t be a riddle.

Posted in Riddles

I Used to Be The Light of Your Life

I used to be the light of your life,
I’d keep you warm while I cried,
Now I’m forgotten and tossed away.

What am I?

A candle. They used to be a primary source of light, and to a lesser extent heat. The “crying” is the wax rolling down the candle.

Posted in Riddles
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Answer This Honestly

What question can you never honestly answer yes to?

Are you asleep? (or dead, or conscious, or being silent).

Posted in Riddles

777, 888 and 999

You are given the numbers 777, 888 and 999. Using the numbers once and adding, subtracting, multiplying or dividing, how can you make 999?

(7 x 7 x 7) + (9 x 9 x 8) + ((9 – 8) x 8) = 999
(77 + 7) + 888 + (9 + 9 + 9) = 999

If other operators were allowed, another solution would be 999 modulo (888 x 777). I’m sure there are more solutions.

Posted in Brain Teasers