Questions

The seven elements — helium, neon, argon, krypton, xenon, radon, and oganesson of Group 18 of the periodic table are Noble or Inert gases.

Radon is the heaviest and Helium is the lightest gases of the noble gases.

The simple machine Axe is made up of both the lever arm and a wedge.

Given 

1 = 1 => 1 x 11 = 11

2 = 22 => 2 x 11 = 22

3 = 33 => 3 x 11 = 33

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Similarly,

11 => 11 x 11 = 121.

From the assumption and trial and error method,

last three digits sum must leave the same digit as the answer. It is possible only if the answer must be units digit number leaving tens digit as carry.

And the possible 3rd digit is 5. Since 5 + 5 + 5 = 15 

Now, 2nd step is  1 + x + x + x = 5

=> 3x = 4

It is possible with x = 8. 8 + 8 + 8 + 1 = 25 leaving 2 as carry. 

Now, 3rd step is 2 + x + x + x = 5 => x = 1

Hence, the three dgits are 1, 8, 5.

185 + 185 + 185 = 555. 

Sulphur is an yellow element that stinks when burned.