Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

In a rainy season, one day 3 huge ladies walked under a normal-sized umbrella.
The umbrella is not huge enough to accommodate all 3 ladies yet not a single lady got wet. Why?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

In a science lab, a petri dish hosts a healthy colony of yeast for an experiment. Now every minute, all the yeast cells divide into two. At noon, there was just a single cell of yeast and at 1:22, the Petri dish was half full. Can you calculate when the dish will be full of yeast?

Can you write down eight eights so that they add up to one thousand?

If you had an infinite supply of water and 5-quart and 3-quart pails, how would you measure exactly 4 quarts? What is the least number of steps you need?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

Solve the equation in the image by looking at the pattern closely.

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?