Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

What has many keys but can’t open a single lock?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

The first two letters signify a male, the first three letters signify a female, the first four letters signify a great, while the entire world signifies a great woman. What is the word?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

There is a box. The area of its top is 240 square units, the area of the front is 300 square units and the area of the end is 180 square units.

Can you calculate the dimensions of this box with the given data?

Which English verb becomes past tense just by rearranging the letters?

If two fifty-foot ropes are suspended from a forty-foot ceiling that is twenty feet apart, how much rope will you be able to steal if you have a knife?

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?