B = (1 - p%) × A = ? Decrease numbers by percentages of their initial values (calculate the numbers decremented by percentage) and calculate the actual change (the absolute difference)

Decrease numbers by percentage of their values, calculate the percentage decreased values

The number 12,000 decreased by 77% (percent) of its value = 2,760	Dec 07 06:22 UTC (GMT)
The number 40 decreased by 14.3% (percent) of its value = 34.28	Dec 07 06:22 UTC (GMT)
The number 8,335 decreased by 38% (percent) of its value = 5,167.7	Dec 07 06:22 UTC (GMT)
The number 100,000 decreased by 0.78% (percent) of its value = 99,220	Dec 07 06:22 UTC (GMT)
The number 250 decreased by 80% (percent) of its value = 50	Dec 07 06:22 UTC (GMT)
The number 10,080 decreased by 286% (percent) of its value = - 18,748.8	Dec 07 06:21 UTC (GMT)
The number 138 decreased by 10% (percent) of its value = 124.2	Dec 07 06:21 UTC (GMT)
The number 0.76 decreased by 37% (percent) of its value = 0.4788	Dec 07 06:21 UTC (GMT)
The number 3,675 decreased by 21% (percent) of its value = 2,903.25	Dec 07 06:21 UTC (GMT)
The number 290 decreased by 1% (percent) of its value = 287.1	Dec 07 06:21 UTC (GMT)
The number 48 decreased by 75% (percent) of its value = 12	Dec 07 06:21 UTC (GMT)
The number 3,280 decreased by 28% (percent) of its value = 2,361.6	Dec 07 06:21 UTC (GMT)
The number 400 decreased by 225% (percent) of its value = - 500	Dec 07 06:21 UTC (GMT)
All the numbers decreased by percentages of their values

Percentage decreased number = Initial value - Absolute percentage change (difference)
Absolute percentage change (difference) = Percentage decrease % × Initial value
Percentage decreased number = Initial value - Percentage decrease % × Initial value = (1 - Percentage decrease %) × Initial value
In conclusion:
Percentage decreased number = (1 - Percentage decrease %) × Initial value
Initial value = ^{Percentage decreased number} / _{(1 - Percentage decrease %)}
Absolute percentage change (difference) = Percentage decrease % × Initial value = New value - Initial value

If Percentage decrease % = 20%, (1 - Percentage decrease %) = 1 - 20% = 100/100 - 20/100 = 80/100 = 0.8 =>
Percentage decreased number = 0.8 × Initial value, and Initial value = Percentage decreased number / 0.8; Absolute percentage change (difference) = New value - Initial value;

If Percentage decrease % = 5%, (1 - Percentage decrease %) = 1 - 5% = 100/100 - 5/100 = 95/100 = 0.95 =>
Percentage decreased number = 0.95 × Initial value, and Initial value = Percentage decreased number / 0.95; Absolute percentage change (difference) = New value - Initial value;

If Percentage decrease % = 120%, (1 - Percentage decrease %) = 1 - 120% = 100/100 - 120/100 = -20/100 = -0.2 =>
Percentage decreased number = -0.2 × Initial value, and Initial value = Percentage decreased number / -0.2; Absolute percentage change (difference) = New value - Initial value;

If Percentage decrease % = -30%, (1 - Percentage decrease %) = 1 - (-30%) = 1 + 30% = 100/100 + 30/100 = 130/100 = 1.3 =>
Percentage decreased number = 1.3 × Initial value, and Initial value = Percentage decreased number / 1.3; this is in fact a percentage increase of the initial number; Absolute percentage change (difference) = New value - Initial value.