DAY 320

Add nine 8's to get 9,000.

Answer:

8888 + 88 + 8 + 8 + 8 = 9000

DAY 319

What is the 1,000th prime number?

Answer:

7, 919

DAY 318

A 20-question test had a possible score of 200 points. 10 points were given for each correct answer and 5 points were deducted for every wrong answer. Your score was 140. How many questions did you get wrong?

Answer:

4..........A score of 140 means you lost 60 points. For every wrong answer, you lose 10 points plus the 5-point penalty, or 15 points. 60/15 = 4

DAY 317

You have two magic pills. One increases your life span by 10% and the other decreases it by 10%. You don't know which pill is which. You take one of the pills. But then you start to worry, so you take the other one to counteract it. Will you now have a normal life span?

Answer:

No......... 1.1 X 0.9 = 0.99

You've lost 1%.

DAY 316

Jim worked overtime and earned an extra $700. This tripled his normal pay. What was his normal pay?

Answer:

$350

Let x = normal pay

x + 700 = 3x

DAY 315

Friends A, B, and C have 100 baseball cards between them. A has twice as many as B, and 10 more than C. How many cards does each person have?

A = 44

B = 22

C = 34

A = A

B = A/2

C = A -10

A + B + C = 100

A + A/2 + (A-10) = 100

2A + A + 2A - 20 = 200

5A = 220

A = 44

B = 22

C = 34

DAY 314

Why do so many alarm clocks have a 9-minute "snooze" interval?

Answer:

After nine minutes, the last digit of the time will be one less that it was nine minutes before (6:15 + 9 minutes = 6:24). Having to monitor only one digit must somehow simplify the electronics of the clock.

DAY 313

A pet store owner sells canaries and cages. If he puts one canary per cage, he has an extra canary. If he puts two canaries in each cage, he has an extra cage. How many canaries and how many cages does he have?

Answer:

4 canaries and 3 cages

x = canaries

y = cages

x = y +1 (one canary per cage)

x = 2y -2 (two canaries per cage)

y + 1 = 2y -2

y = 3

x = 4

DAY 312

In a contest to guess how many gumballs are in a jar, the guesses are 45, 41, 55, 50, and 43. All these guesses are wrong. They are off by 3, 7, 5, 7, and 2 (but not in that order). How many gumballs are in the jar?

Answer:

48.........Since two guesses were off by 7, and no other guesses were repeated, these values must refer to numbers at the opposite sides of the spread. The two extreme are 41 and 55.

41 + 7 = 48

55 - 7 = 48

DAY 311

Add six ones to get 24.

Answer:

11 + 11 + 1 + 1 = 24

DAY 310

Use eleven 8's to make 10,000, using any math operations you want.

Answer:

88888/8 - 8888/8 =

11111 - 1111 =

10,000

DAY 309

How can you change ELUSIVE to EXCLUSIVE using math?

Answer:

Add 90 (XC in Roman numerals)

DAY 308

What are the two non-zero factors of 1,ooo,ooo,ooo?

Answer:

1,000,000,000 = 10 to the ninth power = (2 X 5) to the ninth =

2 to the ninth X 5 to the ninth =

512 X 1, 953,125

(This could also be solved using prime factorization.)

DAY 307

The same letter can go in all three blanks to make this statement true. What's the letter?

1 _ = 1000 _ _

Answer:

M..... 1 Meter = 1000 Millimeters

DAY 306

What digit is in the ones' place in the product of the first 1000 prime numbers?

Answer:

Zero..............This colossal number would have to end in zero because 2 and 5 are prime numbers, and any number multiplied by 10 will have a zero in the ones' place.

DAY 305

The same three digits, when added together, equal 12.

There are two solutions.

One is: 4 + 4 + 4 = 12.

Can you determine the other?

Answer:

1 + 11 = 12

DAY 304

If a clock strikes the number of the hour in the usual way (i.e. nine strikes for nine o'clock), and just once on the half-hour, what time is it if the clock has struck three single times?

Answer:

1:30...........The clock struck once at 12:30, once at 1:00, and once at 1:30

DAY 303

A farmer grew a delicious apple which he wanted to take to the king. The castle was surrounded by seven gated walls, with a guard at each gate. At the first gate, the farmer asked if he could go through to see the king.

GUARD: You may go through if you give me 1/2 of you apples.

FARMER: I will, but you must give back one.

GUARD: Agreed

This was repeated with each of the seven guards. When the farmer got to the king, he had the same number of apples he started with. How many?

Answer:

Two

DAY 302

What is unusual about the following subtraction problem?

954 -459 = 495

Answer:

The minuend, subtrahend, and difference are all made up of the same digits, but in a different order. In each, two of those digits (4 and 5) add up to the third digit (9).

DAY 301

Two men starting at the same point walk in opposite directions for 4 feet. Each turns left and walks another three feet. What is the distance between them?

Answer:

10 feet

When the men turn left, one is walking "up" and one is walking "down" ------------- creating two right triangles with legs of 3 and 4 feet. This is a Pythagorean triple, so the hypotenuse of each triangle is 5 feet. The men are separated by the distance of two 5-foot hypotenuses.

DAY 300

Split 34 into two parts such that 4/7 of one part equals 2/5 of the other.

Answer:

14 and 20.........Let x and y be the two parts:

x + y = 34

4/7 x = 2/5 y

x = 14/20 y

14/20 y + y = 34

14 y + 20 y = 680

34 y = 680

y = 20

It follows that x= 14

Check:

4/7 of 14 = 8

2/5 of 20 = 8

DAY 299

Add two lines to make this equation valid:

25 = 410

Answer:

2/5 = 4/10