Can you fill the blank with the correct number?

6 30 870 756030 _____

Spot what is wrong here in below Picture?

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

On 26-01-2022, Juli was murdered at her house in a city in India in the afternoon. There were three suspects in the murder and the following are the statements that were given by them:

John: I visited my village that day.
Jacob: I was out to deposit my house tax in the municipality office at that time.
Jonny: I was at a friend's place having lunch at that time.

Can you find out who is the murderer?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

O_er_t_o_

Complete the missing letters of the given word.

What is so fragile that saying its name breaks it?