Seemingly Simple Math

What is the answer to this math problem:

8 ÷ 2 (2 + 2)

16 or 1, depending.

According to PEMDAS, parentheses come first: 8 ÷ 2 (4)

Then, even though multiplication is first in PEMDAS, you go left to right: 4 (4) = 16

If you got 1, you’re in good company. That’s what I got at first too but most calculators I’ve tried get 16.

I found this at Popular Mechanics and the debate continues online.

Posted in Brain Teasers

Progressive Countdown

If you’re given a number, subtract 1, then 2 from the result, then 3 from that result and so on until you reach 0 or a negative number.

For example, if you’re given 15:

15 – 1 = 14
14 – 2 = 12
12 – 3 = 9
9 – 4 = 5
5 – 5 = 0

Which of these numbers will finish exactly at zero?

102 103 104 105 106

105

105 – 1 = 104
104 – 2 = 102
102 – 3 = 99
99 – 4 = 95
95 – 5 = 90
90 – 6 = 84
84 – 7 = 77
77 – 8 = 69
69 – 9 = 60
60 – 10 = 50
50 – 11 = 39
39 – 12 = 27
27 – 13 = 14
14 – 14 = 0

Posted in Brain Teasers

100 Less Than 99

Where do you find that 100 is less than 99?

On a microwave. Most microwaves will run for a minute if you enter 100, but will run for a minute and 39 seconds if you enter 99.

100 is also less than 99 in an ordered ranking, where 1 is first, and 100th is a lower rank than 99th place.

Posted in Brain Teasers

I Met An Old Man On London Bridge

I met an old man on London bridge,
As the sun set on the ridge,
He tipped his hat and drew his name,
And cheated at the guessing game.

What was the man’s name?

Andrew. In the third line, “and drew his name”. It works better when you say it since the spelling is a bit off when written.

Posted in Riddles

Forever Stuck

I can’t go right,
I can’t go left.

I’m forever stuck going only up and down.

What am I?

An elevator.

Posted in Riddles

Useless Keys

What keys don’t unlock any doors?

Piano keys, keyboard keys, monkey, donkey, turkey, jockey, hockey, doohickey, malarkey and passkey. There may be others, but you get the drift.

Posted in Brain Teasers

An Attorney for a Brother

The defendant testified, “The attorney is my brother,” but the attorney took the stand and denied having a brother under oath. Who is lying?

Neither one of them lied. The defendant was the attorney’s sister.

Posted in Brain Teasers

Two Three Ten Sequence

If:
2 3 = 10
7 2 = 63
6 5 = 66
8 4 = 96
9 7 = __

What is the missing number?

f(n, m) = (n + m) × n

e.g. f(2, 3) = (2 + 3) × 2 = 10

Hence, f(9, 7) = (9 + 7) × 9 = 144

Posted in Brain Teasers
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Fourth of July in England

Is there a 4th of July in England?

Yes, there’s a 4th of July in every country. Of course they don’t treat it as a holiday as citizens of the United States do, but that’s not what was asked.

Posted in Brain Teasers

A Trapped Flock of Birds

A flock of birds are trapped in a delivery truck. When would the truck weigh the most?

a) When the birds are resting on the floor
b) When they’re all flying
c) The weight remains the same

c – The weight doesn’t change since it’s a closed system.

Posted in Brain Teasers