I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

If,

Akriti = 631
Levis = 521
Sroti = 521
Aneel = 533
Then,
Sunil =?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

Chhote se Chintu Miyan,
Lambi si Pooch.
Jahan Jaye Chintu Miyan,
Wahan Jaye Pooch.

छोटे से चींटू मियाँ,
लंबी सी पूंछ।
जहाँ जाये चींटू मियाँ,
वहाँ जाये पूंछ।

Bolo kya?

Spot what is wrong here in below Picture?

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?