Finding an original value before compound change
The original amount is 100%. For a
- The original amount is 100%. For a
% increase, the multiplier is = ( ) ÷ 100; for a decrease use ( ) ÷ 100. - After
equal periods, final amount = original amount × to the power . - Work backwards by dividing the final amount by
to the power . Do not subtract the percentage times.
Example 1
After 2 years of compound growth at 2% per year, a value is £520.20. Find its original value.
Example 2
After 2 years of depreciation at 3% per year, a value is £470.45. Find its original value.
Remember
Use the worked steps to check your method, not just the final answer.
Your turn
After 2 years of compound growth at 4% per year, a value is £540.80. Find its original value.
Check answer
After 2 years of depreciation at 5% per year, a value is £451.25. Find its original value.
Check answer
After 2 years of compound growth at 6% per year, a value is £561.80. Find its original value.
Check answer
After 2 years of depreciation at 7% per year, a value is £432.45. Find its original value.
Check answer
After 2 years of compound growth at 8% per year, a value is £583.20. Find its original value.
Check answer
After 2 years of compound growth at 4% per year, a value is £540.80. Find its original value.
AnswerAfter 2 years of depreciation at 5% per year, a value is £451.25. Find its original value.
AnswerAfter 2 years of compound growth at 6% per year, a value is £561.80. Find its original value.
AnswerAfter 2 years of depreciation at 7% per year, a value is £432.45. Find its original value.
AnswerAfter 2 years of compound growth at 8% per year, a value is £583.20. Find its original value.
Answer