Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

Why Wine Glass Stem is so long?

If two's company, and three's a crowd, then whats four and five ?

On her drawing table, Sayna lit 12 coloured candles. A few seconds later she blew two candles off.

How many candles Sayna have at the end?

You are provided with a grid (as shown in the picture). Can you fill the squares with numbers 1-8 in a manner that none of the two consecutive numbers are placed next to each other in any direction (vertically, horizontally or diagonally?)

Prove that twice of ten is the same as twice of eleven.

Two batsman each on 94 runs. Seven runs needed to win in last 3 balls. Both make 100*. How?

Can you find out which options fits best with the missing column?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Christina is practising her dance steps along with her friends. In a particular sequence, all of them form a row. At that point, Niharika is standing in the 4th position from either end of the row.
Can you find out how many girls are practising together?