40 Prompts to Ask Your AI Assistant When a Calculator Is Connected

Short answer: if your AI assistant has a calculator connected, the best prompts name the numbers, say what you want worked out, and ask the assistant to show the inputs it used. Below are 40 prompts grouped by topic. Each one is mapped to the Mathify calculator the assistant would use. We list prompts only, with no sample answers, because the result depends on your numbers.

How do I get an assistant to use a calculator instead of guessing?

Connect Mathify as a remote MCP server first. The steps are in the guide to connecting Mathify calculators to an AI assistant, and the reason it helps is explained in why chatbots get math wrong. In short, the assistant can search the available calculators, read what inputs one needs, run it and report the returned value.

Five habits make prompts work better:

1. Give the numbers, with units. "180 lb" rather than "my weight".
2. Say which calculator or method you mean when it matters. "Compound monthly" is not the same as "compound annually".
3. Ask for the inputs back. "List the inputs you used" lets you catch a misread number.
4. Ask for the link. The tool result includes a page link, which you can open to check or share.
5. Treat missing inputs as a question, not a gap to fill. Tell the assistant to ask you rather than assume.

A growing set of Mathify calculators can be run this way. If a calculator is not available as a tool, an assistant can still point you to its page.

Percentages and everyday math

• "Use a calculator to find 15% of 850 and show the inputs you used." Calculator: Percentage Calculator
• "What is the percent change from 4% to 5%, and how many percentage points is that?" Calculator: Percentage Calculator
• "A jacket costs 120 and is 35% off. What is the sale price?" Calculator: Discount Calculator
• "Add 8.25% sales tax to a 64.20 purchase and show the total." Calculator: Sales Tax Calculator
• "Convert 0.375 to a percentage and to a fraction." Calculator: Percent Converter
• "Simplify the ratio 48:36 and say how it scales to 100." Calculator: Ratio Calculator

Dates and time

• "How many days are there from 1 March 2026 to 15 October 2026?" Calculator: Date Difference
• "I was born on 12 May 1990. What is my exact age today in years, months and days?" Calculator: Age Calculator
• "How many days old am I if I was born on 3 September 2001?" Calculator: Age in Days
• "What date is 90 days after 15 October 2026?" Calculator: Add and Subtract Time
• "How many business days are there between 1 and 31 December?" Calculator: Business Days Calculator
• "What day of the week was 4 July 1999?" Calculator: Day of the Week
• "Count down the days to 1 January 2027." Calculator: Countdown

Loans and mortgages

• "What is the monthly payment on 300,000 at 6.5% over 30 years?" Calculator: Mortgage Calculator
• "Show the EMI for a 500,000 loan at 9% for 5 years." Calculator: EMI Calculator
• "Compare total interest on a 20,000 car loan at 5% over 4 years versus 6 years." Calculator: Auto Loan Calculator
• "If I refinance for a lower rate and pay 3,000 in costs, when do I break even?" Calculator: Refinance Break-Even
• "How long will it take to pay off a 4,500 credit card balance paying 200 a month?" Calculator: Credit Card Payoff
• "What is my debt-to-income ratio with 2,100 in monthly debt payments and 6,000 gross monthly income?" Calculator: Debt-to-Income

Savings, interest and growth

• "How much is 10,000 worth after 10 years at 5%, compounded monthly?" Calculator: Compound Interest Calculator
• "What is the simple interest on 1,000 at 5% for 180 days?" Calculator: Simple Interest Calculator
• "Convert a 4.25% APR compounded monthly into APY." Calculator: APY vs APR
• "How long until money doubles at 6% a year?" Calculator: Rule of 72
• "What is the annual growth rate if an investment grew from 5,000 to 8,200 in 6 years?" Calculator: CAGR Calculator
• "What would 100 a month in a SIP at 12% a year be worth in 15 years?" Calculator: SIP Calculator

Business and pricing

• "My cost is 80 and I sell at 100. What are my markup and margin?" Calculators: Markup and Margin
• "Fixed costs are 6,000 a month, price is 40 and variable cost is 15. What is my break-even volume?" Calculator: Break-Even Calculator
• "Work out the ROI if I spent 2,000 and got back 2,600." Calculator: ROI Calculator
• "Convert a 52,000 yearly salary to an hourly rate." Calculator: Salary to Hourly
• "Split an 87.50 bill with an 18% tip between 3 people so the cents add up." Calculator: Bill Split

Health and fitness

These are general estimates, not medical advice.

• "Calculate BMI for 180 lb and 5 ft 10 in." Calculator: BMI Calculator
• "Estimate my daily calorie needs from my age, height, weight and activity level." Calculator: Calorie Calculator
• "What is my 5K pace if I run it in 27 minutes 30 seconds?" Calculator: Pace Calculator
• "How much water should a 75 kg adult aim for?" Calculator: Water Intake

Units and home projects

• "Convert 180 pounds to kilograms using the exact factor." Calculator: Weight Converter
• "How many litres are in 10 UK gallons, and how many US gallons is that?" Calculator: Volume Converter
• "Convert 30 US mpg to UK mpg." Calculator: Fuel Economy
• "How many square feet is a 12 by 15 foot room, and how much paint covers it?" Calculator: Paint Calculator
• "How many cubic yards of concrete for a 10 by 12 foot slab, 4 inches thick?" Calculator: Concrete Calculator

Statistics

• "Find the mean, median and mode of 4, 8, 15, 16, 23, 42." Calculator: Mean, Median and Mode

Those are all 40 prompts. Change the numbers to yours and adjust the wording.

What should I check in the assistant's answer?

A tool-backed answer is more reliable than a guess, but check these four things:

• Inputs. Did it use your numbers, with the right units and the right period (monthly or yearly)?
• Method. Did it choose the calculation you meant (simple or compound, margin or markup)?
• Rounding. Is the figure rounded for display, and by how much?
• Fit. Does the calculator match your situation? Mortgage fees, local tax rules and clinical advice sit outside a generic formula.

Common mistakes

• Leaving out units, so the assistant has to guess pounds or kilograms.
• Not stating the period, such as an annual rate with monthly payments.
• Asking for a "quick estimate" and expecting an exact figure.
• Accepting a number with no inputs listed.
• Using a result for a legal, tax or medical decision without checking an official source.

Key takeaways

• Name the numbers, the units and the method.
• Ask the assistant to list its inputs and give the calculator link.
• Check the direction and size of the answer against common sense.
• Finance and health results are information, not advice.

FAQ

Do I need to name the calculator in my prompt?

No. An assistant with the connector can search for a matching calculator from a plain description. Naming one helps when several are similar, such as markup and margin.

Do these prompts work with any AI assistant?

They work with any assistant that supports custom connectors or remote MCP servers and has Mathify connected. Without a connector, an assistant may still answer, but it is then writing the numbers itself.

What if the assistant says it cannot run a calculator?

Not every calculator is available as a tool. Ask the assistant for the calculator's page link and enter the numbers there.

Can I make the assistant show how the answer was worked out?

Ask it to include the formula and steps. The tool returns these where the calculator provides them.

Are the results financial or medical advice?

No. They are arithmetic on the numbers you supply. For decisions about money or health, consult a qualified professional.