.0066666666 × $100,000 × 120
1  (1 + .0066666666) ^{120}
Which equals:
[ .0066666666 × $100,000 × 120 ] ÷ [ 1  (1 + .0066666666) ^{120} ] =
[ 80,000 ] ÷ [ 1  (0.45052346071062) ] =
80,000 ÷ 0.54947653928939 =
$145,593.11
Do you want to solve for:
Input should only consist of numbers and decimal points.
Do NOT use commas, dollar signs or per cent signs.

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The above formula is used to calculate the principal of a loan if you know the total cost, interest rate and number of payments.
We'll use the previous data.
We have paid a total of $145,593.11 for a 10 year loan at 8% interest.
What was the principal?
Using the above formula, the principal would be:
145,593.11 145,593.11 × (1.00666666666666)^{120}
.00666666666666 × 120
Which Equals:
145,593.11 145,593.11 × 0.450523460710793 =
.8
145,593.11 65,593.11 =
.8
100,000.00
