I am white when I am dirty, and black when I am clean. What am I?

A gardener planted the Lemon trees in a mathematical ordered way (i.e. he planted a tree in rows).
He created a total of 19 rows of trees.

Note: There should be more than 2 trees to count as a row.

What is the minimum number of trees required by the gardener to have 19 rows of trees?

Three people check into a hotel. They pay $60 for the rent of the room. After they check-in, the manager realize that the rent for the room is $55. So, he gives $5 to the bellboy and asks him to give it to them. The bellboy thinks that it will be difficult for the three people to share $5 among them and seeking the personal benefit, he pockets $2 and gives the remaining $3 to them.

Now, each person paid $20 and got back $1. In this manner, each of them paid just $19 which totals to the amount of $57. The bellboy has $2 with him and adding them, we get $59. So where is the remaining $1?

Seek and Puzzle: Only the Sharpest Eyes Can Spot the Hidden Star in 10 Seconds

What number do you get when you multiply all of the numbers on a telephone's number pad?

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

Can you find the odd one out from the below words ?

First Second Third Forth Fifth Sixth Seventh, Eighth Nine Ten Eleven Twelve.

Find the next number in the sequence

1, 2, 6, 21, 88, __?

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

Cristina was born in 1888. She just had her 30th birthday today how did that happen?