What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

What is greater than gold but cannot be bought. it can never be sold and can earn if its sought. though it can be broken, it can still be fixed. for by birth it can't start nor by death it is ended.what am i?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

When 99 is considered higher than 100?

What does this Rebus Picture mean?