Question

to increase an amount by 22%, multiply by...

Answer 1

1.22 / 1,22

because:
100% of 100 is 100. You multiplied it by one.
110% of 100 is 110. You multiplied it by 1.1 / 1,1

So if you want to multiply by a percentage between 100 and 200 you have to multiply by a number between 1 and 2.