Sixteen, Twenty-six, Then What?

Fill in the missing numbers in this number series.

16, 26, ?, 43, 50, ?, 61, 65, ?, 70, 71

The method to create the series is start by adding 10, then decrease the addend by 1 for each new number in the sequence. That gives us:

16 + 10 = 26
26 + 9 = 35
35 + 8 = 43
43 + 7 = 50
50 + 6 = 56
56 + 5 = 61
61 + 4 = 65
65 + 3 = 68
68 + 2 = 70
70 + 1 = 71

Posted in Brain Teasers

Ten Plus Ten Equals Ten

When can ten plus ten equal ten, yet ten minus ten equal twenty?

When putting gloves on then removing them.

Posted in Brain Teasers

Early Ages The Iron Boot Tread

Early ages the iron boot tread,
with Europe at her command.
Through time power slipped and fled,
’til the creation of new holy land.
Who am I?

Italy / Rome.

Posted in Riddles

Arms and Legs But No Head

What has arms and legs but no head?

A chair.

Posted in Riddles

What Boys Use, Girls Like and Parents Hate

Boys use it, girls like it, parents hate it. What is this 5-letter word?

The phone.

Posted in Riddles

Three Pills From the Doctor

Your doctor gives you three pills and tells you to take one every half hour. How much time will have passed by the time you’ve taken all three pills?

One hour. You take the first pill, then wait a half hour and take the second pill, then at the hour mark you take the third and last pill.

Posted in Brain Teasers

A Corny Question

A merchant has 21 sacks of grain: 7 full, 7 half-full and 7 empty. He wants to divide them equally among his three sons. How can he do this, without transferring any grain between sacks, so each son has the same quantity of grain and number of sacks?

We know each son must end up with 7 sacks and 3.5 sacks of grain, since (7 sacks + 7 half sacks) / 3 = 3.5 sacks each.
There are two solutions.

Solution 1
Son 1: 3 full, 1 half-full and 3 empty.
Son 2: 3 full, 1 half-full and 3 empty.
Son 3: 1 full, 5 half-full and 1 empty.

Solution 2
Son 1: 2 full, 3 half-full and 2 empty.
Son 2: 2 full, 3 half-full and 2 empty.
Son 3: 3 full, 1 half-full and 3 empty.

Posted in Brain Teasers

The Old Gray Surgeon

A man and his son had a terrible car accident and were rushed to the hospital. The man died on the way, but the son was still barely alive. When they arrived, an old gray surgeon was called in to operate. Upon seeing the young boy, the surgeon said, “I can’t operate – this is my son.”

How is this possible?

The surgeon was the boy’s mother.

Posted in Brain Teasers

ABCD equals DCBA

What 4-digit number abcd satisfies this equation?

4 × abcd = dcba

2178

4 × 2178 = 8712

Posted in Brain Teasers

Odd Row Out

Which row is the odd one out?

A.KNQTWZ
B.BFJNRV
C.AFKPVZ
D.369121518
E.71115192327
F.131823283338

C is the odd row out.

In A two letters are skipped between each letter.
In B three letters are skipped between each letter.
In C four letters are skipped between each letter except V, which should be U.
The numbers in rows D, E and F follow the same pattern.

Posted in Brain Teasers