This website contains online computational modules dealing with various subject such as loudness/noise pollution, saving money, enterprises, and health. Remember this website under one of the following names:

1. www.computeit.info
2. www.computeit.eu
3. www.numericalexample.com
4. www.numericalexample.eu
5. www.hisaab.in

The use of the forms in the modules is explained for each numerical example.  Note however that one can enter his own formulas in the fields of each form as well.

For instance in the savings numerical example one can take transaction costs of periodic savings into account. If the monthly savings are $ 100 and the transaction costs are each month 2 % then one should enter "0.98*100" in the monthly savings field.

This website hosts several calculators computing an effective return on investment. This can be a capital gain on investments on the stock market, an effective interest rate, a value increase of a house you own, etc. These calculators typically take (periodic) withdrawals and deposits into account, or convert between interest periods, or take (periodic) costs into account. The table below gives a list of these calculators together with a short description and any example computations.

The purpose of the examples is to demonstrate the use of the calculators, to give you an idea of how to use each particular calculator. In many cases you will need to change the calculator input such that it corresponds better to your real life situation.

With this module you can compute dates during and after your pregnancy.

If you enter a negative value for "Days before birth", "Weeks before birth", or "Months before birth" then the result that will be printed after it will indicate the days, weeks, or months after the birth date.

With this numerical module you can not compute the conception date from the birth date. It is more accurate to compute the conception  date from the date of the beginning of the last menstruation. If you still want to have an indication of the conception date given the birth date then go to the conception date calculator.

The abreviation PAL stands for Physical Activity Level. This is a way to express your daily physical activity in a number. This number is defined as a multiple of your Basal Metabolic Rate, which is the amount of energy you consume if you sleep. The PAL factor can be used to compute the amount of calories one must eat.

If you need to loose much weight then your PAL value should be at least 2.

With this numerical example you can compute how much your money grows in time. Alternatively you can compute how long it takes before you have spent it all. You can enter the amounts you save or withdraw per month and per year. Use a minus sign for money withdrawn from your bank account.

Do not forget to enter the amounts that you receive or withdraw on a yearly basis, like your bonus.

Often the monthly and yearly saved amount varies per year. For some people this amount increases each year, for others spendings go up faster than income, for instance because of inflation. This effect can be modelled by increasing or decreasing the monthly and yearly savings each year with a certain percentage.

While cooking meals, for example an instant meal, most people first read a recipe or at least the directions on the wrapping of the meal. When a microwave must be used these directions give the cooking time at a certain power of the microwave.

But what to do if your microwave does not have the right power level ? Or what to do if you want to speed things up by putting your microwave at a higher power ? Or you might want to slow down the cooking because you want the microwave to be ready simultaneously with other parts of your meal. Another possibility is that you want to prepare a meal for more persons than in the meal of the recipe. So you have to adjust the amounts of your ingredients.

In the above situations you can either compute the alternative power of your microwave or the cooking time.

Personal injury can be caused in an accident: in the traffic, during sporting, at home, at school or at work. Injury can also be caused by medical mistakes, or criminal offenses. Victims of personal injury may be entitled to compensatory damages, if the injury was caused by someone else or if the event are covered by an insurance. Such damages are:

• Loss of income or earning capacity,
• Compensation for loss of life quality caused for example by pain, disability, or emotional distress,
• Extra costs, for example medical costs.

Usually the damages are suffered on a yearly basis but the compensation payment is a once-off payment. This calculator computes this once-off payment. After receiving the once-off payment it shows a graph with the remaining amount for every year. The calculator also shows a second graph with yearly amounts that should be paid if the compensation is paid on a yearly basis.

The future value of this payment is influenced by the following factors:

• the interest rate,
• the inflation,
• taxes: wealth tax and tax on interest

The higher the expected long term interest rate is, the lower the damages paid need to be to compensate for example a loss of income. Similarly the higher the inflation and taxes are the higher the damages need to be.

Buying a house is not easy. Everyone in the family has his or her own wishes: a modern kitchen, a garden, close to work, in a quiet environment, not too much maintenance, etc. Many people also want a bigger house. With this online calculator you can compute the inside area of a house or compare the area's of two different houses.

One of the most important financial decisions deals with which car we should drive, if any at all. Few people know how much driving costs because these costs are difficult to estimate. Especially the variable car costs are difficult to estimate mainly because people do not exactly know how much they drive. The computation is not difficult but still lengthy, too lengthy to do without a computer. Neither do most people know for which purpose they drive, for business or private purposes, which is usually also an important factor in decision making.

With this calculator you can estimate how much you drive and how many miles are for private purposes and how many miles for business purposes. You will also get an estimate of the variable costs, including garage costs, fines, parking costs, and fuel. In addition the computation keeps track of which variable costs are made for business purposes and which costs are private.

Compute the loudness of a point source at a certain distance, based upon a measurement at a different distance.

The theory of this numerical example is described at www.natuurkunde.nl, in dutch. The theory describes exponential dissipation of sound with distance and decay with distance according to the inverse square law. The theory does not take into account the effect of the soil, barriers, reflections, wind, and atmospheric effects.

By adding the loudnesses of multiple point sources you can model more complex sources of sound. Adding the loudnesses of sound sources can be done with this calculator. For instance three point sources on a line form an elementary sound model for a road.

People older than 40 usually need an extra pair of glasses for reading. With this calculator you can compute what kind of reading glasses you need.

This module computes one of the following given the other loan/mortgage parameters:

1. maximum loan: amount excluding costs,
2. interest,
3. term amount,
4. remaining debt,
5. number of terms.
   

The parameters are calculated using the costs as well. Three results are computed, one for linear loans, one for annuity loans and one for interest-only loans. 

With a linear loan we mean that at every term the same amount is payed back. On top of that interest is paid at the beginning or end of every term. Because the remaining debt decreases after each term the amount of interest to be paid becomes smaller at the end of the loan period. So the amounts for the first terms are higher than the amounts for the last terms. 

For annuity loans a constant amount is payed at each term. In the beginning of the loan this amount usually mainly consists of interest. Later on the amounts payed at each term contain less interest and the remaining debt decreases faster over the terms. 

For an interest-only loan only interest will be paid at each term. At the end of the last term the remaining debt is the original amount plus the transaction costs. The computed monthly amount is equal to the interest part of the first term of a linear loan. For a large number of terms the same is aproximately true for the interest part of the first terms of an annuity loan.

Compute the total loudness of two or more sources.

Combine the results of this numerical module with the numerical example computing sound levels at a different than measured distance.

Estimate your profit if you have a small company, such as a company of a contractor, plumber, hairstyler, driving instructor.

Numerical examples related to growth and weight. This includes your weight, excercise, pregnancy and the growth of your child.

With this online calculator you can compute the power of the contact lenses you from the power of the glasses you already have. For example this could be necessary if you would like to buy soft lenses over the internet. Despite the fact that you can buy your contact lenses  online you will still need to go to an optician for checkups. An optician need to check your eyes on vascular growth into the cornea, infections and scarring if you wear contact lenses.

You can also compute the opposite: given the power of your contact lenses you can compute the power of the glasses you will need. In addition you can do the same two calculations for glasses on an unusual distance from the eye. For instance for glass(es) of a diving mask that are further away from the eye than the standard distances of 12 and 14 mm. 

Investment funds like mutual funds and ETF's usually provide the yearly (management) costs in their reports. Research has shown that these costs are an important factor in the capital gains that investors achieve through the years. Therefore it is good to check the hidden costs a fund charges before investing in it.

When a fund trades its assets this also costs money. However costs related to trading of fund assets are usually not reported as yearly costs. But with this calculator you can estimate the total costs of an investment fund, including these trading costs. These trading costs consist of the trade commission plus the spread. The spread is the difference between the bid and the ask price.

With this example one can compute the safe maximum dose of two medicins. The example is meant for use by Ophthalmologists. No liability can be accepted for use of this example.

The safe dose can be computed for two medicins: Chloroquine and Hydroxychloroquine (Plaquenil). This dose should be computed based on the patients ideal weight, which is computed from the patients height.

About 20% of the prescriptions contains errors. Therefore it would be ideal if patients would be able to check their prescriptions, and the dosages. I hope this numerical module helps.