Idaho Real Estate Exam Math: Formulas and Practice Problems

Math questions on the Idaho real estate exam test the same core formulas as the national section — plus Idaho-specific applications involving property value and water rights. Here are worked examples for every type of math question you'll encounter.

Commission Calculations

Formula: Commission = Sale Price × Commission Rate

Example: A property in Boise sells for $395,000 with a 5.5% total commission split 50/50 between the listing and buyer's broker. The listing salesperson earns 50% of the listing broker's share. How much does the salesperson earn?

Total commission: $395,000 × 0.055 = $21,725
Listing broker's share: $21,725 ÷ 2 = $10,862.50
Salesperson's share: $10,862.50 × 0.50 = $5,431.25

Loan-to-Value Ratio

Formula: LTV = Loan Amount ÷ Purchase Price

Example: A buyer purchases a home for $310,000 and makes a 10% down payment. What is the LTV?

Down payment: $310,000 × 0.10 = $31,000
Loan amount: $310,000 − $31,000 = $279,000
LTV: $279,000 ÷ $310,000 = 90%

Follow-up: Is PMI likely required? Yes — PMI (private mortgage insurance) is typically required when LTV exceeds 80% on conventional loans.

Proration (Idaho — 365-Day Year)

Example: A seller has prepaid property taxes of $3,650 for the year. Closing is on July 1. How much credit does the seller receive for the prepaid taxes remaining after closing? (Days July 2 through Dec 31 = 184 days)

Daily tax rate: $3,650 ÷ 365 = $10.00/day
Seller credit: $10.00 × 184 = $1,840

Capitalization Rate

Formula: Value = NOI ÷ Cap Rate

Example: An investment property in Coeur d'Alene has a Net Operating Income of $48,000 per year. The market cap rate is 6%. What is the estimated value?

- Value: $48,000 ÷ 0.06 = $800,000

Reverse: If the property is listed at $720,000 and has an NOI of $48,000, what is the cap rate?

- Cap Rate: $48,000 ÷ $720,000 = 6.67%

Gross Rent Multiplier

Formula: GRM = Price ÷ Gross Annual Rent (or Monthly GRM = Price ÷ Monthly Rent)

Example: A duplex sells for $420,000 and generates $2,800/month in gross rent from each unit ($5,600/month total, $67,200/year). What is the annual GRM?

- GRM: $420,000 ÷ $67,200 = 6.25

Points

Formula: 1 point = 1% of the loan amount

Example: A buyer borrows $268,000 and pays 1 discount point to lower their interest rate. How much do they pay in points?

- $268,000 × 0.01 = $2,680

Area Calculations

Formula: Area = Length × Width (rectangles) | Area = 0.5 × Base × Height (triangles)

Example: A rectangular plot of land is 1,320 feet long and 660 feet wide. How many acres is it?

Area: 1,320 × 660 = 871,200 sq ft
Acres: 871,200 ÷ 43,560 = 20 acres

(Note: 1,320 feet = ¼ mile; 660 feet = ⅛ mile — this is a half-section quarter section)

Percentage of Value Change

Example: A property was purchased for $250,000. It sold for $272,500. What was the percentage gain?

Gain: $272,500 − $250,000 = $22,500
Percentage: $22,500 ÷ $250,000 = 9%

Community Property Math Scenario

Example: A husband and wife purchase a home for $400,000 during their marriage using community funds. If they later divorce, what is each spouse's ownership interest?

- Each spouse owns $200,000 (50% each) — the home is community property

Exam Day Math Tips

Write all key formulas on scratch paper immediately when the exam begins
Carry enough decimal places to avoid rounding errors in multi-step problems
Idaho math is the same as national math — no Idaho-specific formulas, but expect water rights context in word problems

For full Idaho practice exams, visit [CARealestate.com/states/idaho](https://carealestate.com/states/idaho).