Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

Can you find the odd number in the following five choices?

1) 482636
2) 259807
3) 865195
4) 104739
5) 391744

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

In the addition below, all digits have been replaced by letters. Equal letters represent equal digits and different letters represent different digits.
ABCABA
BBDCAA
ABEABB
ABDBAA
------- +
AAFGBDH
What does the complete addition look like in digits?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?

Can you find any error in the following sentence?

A taxi was standing outside a fort at night. A man came out of the fort, opened the gate and hit the taxi driver killing him instantly. He took all the money out of the meter and started running till he was caught by a local sheriff.

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

Can you count the number of triangles inside a triangle?

A number with an interesting property:

When I divide it by 2, the remainder is 1.
When I divide it by 3, the remainder is 2.
When I divide it by 4, the remainder is 3.
When I divide it by 5, the remainder is 4.
When I divide it by 6, the remainder is 5.
When I divide it by 7, the remainder is 6.
When I divide it by 8, the remainder is 7.
When I divide it by 9, the remainder is 8.
When I divide it by 10, the remainder is 9.

It's not a small number, but it's not really big, either.
When I looked for a smaller number with this property I couldn't find one.

Can you find it?