Interest can be calculated for loans or for investments.  For a loan, interest is the amount paid to the creditor for granting the loan to you. For an investment, interest is income that the investment earns.  Interest for a loan is usually expressed as an annual percentage rate, which is the annual rate that is charged for borrowing the money.  Interest on an investment is usually expressed as a percentage.  The two main types of interest that can be applied to loans are simple and compound interest. Simple interest is calculated by multiplying the interest by the principal by the number of periods. Compound interest, however, is the most commonly used method of applying interest to a loan or investment. Compound interest is interest calculated on the original principal plus interest calculated on the accumulated interest from previous accounting periods. The rate at which the interest accrues, or accumulates over time, depends on how often the interest is compounded. Interest can be compounded annually, monthly or quarterly.  Compound interest is not beneficial for those in debt. If a person carries a credit card balance on a high-interest credit card for which the interest is compounded monthly, the interest payments alone could be hundreds of dollars per month.  Compound interest is advantageous to investors, because the interest that is earned each accounting period gets added back to the principal and earns more money for the investor. The annual compound interest formula is P(1+i)n−P{\displaystyle P(1+i)^{n}-P}.  In this formula, P = Principal, i = annual interest rate in percentage terms, and n = number of compounding periods. If the interest is compounded more than once per year, such as monthly (12 times per year) or quarterly (four times per year), the formula must be adjusted, The formula for compound interest that is compounded multiple times per year is [P(1+i/n)n∗t]−P{\displaystyle [P(1+i/n)^{n*t}]-P}. In this formula, P = Principal, i = interest rate, n = number of compounding periods, and t = the number of years for which the money is invested or borrowed. You can use the rule of 72 to figure out how long it will take to double your money on an investment that is earning compound interest. Divide 72 by the annual interest rate your investment is earning. The answer will tell you how many years it will take for your investment to double in value.  For example, if your investment is earning a 3 percent interest rate, calculate how long it will take to double your money using the equation 72/3=24{\displaystyle 72/3=24}. In 24 years, your investment will have doubled in value. Interest rates on investments do fluctuate, so the rule of 72 should be used as a tool for estimating the future value of your investments.
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One-sentence summary -- Understand the meaning of interest. Define compound interest. Learn the formula for compound interest. Understand the Rule of 72.

Q: Before you begin to calibrate and use your pH meter you will first need to turn it on and allow adequate time for the meter to warm up. This should generally take around 30 minutes, but check your pH meter's operating manual for exact times. Take the electrode out of its storage solution and rinse it with distilled water under an empty waste beaker. Once rinsed, blot dry with Kimwipes or Shurwipes, which are available at most office supply stores.  Be sure to rinse your electrode in a waste beaker that is different from the beaker you will be calibrating in.  Avoid rubbing the electrode as it has a sensitive membrane around it. If you find the electrode to be particularly dirty consult your operating manual for recommended cleaning solutions. You will generally need more than one buffer for calibrating a pH meter. The first will be a “neutral” buffer with a pH of 7, and the second should be near the expected sample pH, either a pH of 4 or 9.21. Buffers with a higher pH (9.21) are best for measuring bases, whereas buffers with a low pH (4) are best for measuring acidic samples. Once you have chosen your buffers allow them to reach the same temperature as the pH meter because pH readings are temperature dependent. Pour your buffers into individual beakers for calibration.  Check with your pH meter manufacturer, or current educational or professional institution, about acquiring pH buffer solutions. Buffers should be kept in a beaker for no longer than two hours. Discard the buffer when you are finished. Do not return it to its original container.
A: Turn on your pH meter. Clean your electrode. Prepare your buffers.

Article: Do you know how long you are willing to be long distance? Does your partner know? It is important to agree on a length of time. If the distance depends on a circumstance with no certain end date, your reunion may keep getting pushed off. Make sure that you discuss the financial aspects of maintaining your relationship with your partner as well. Being in a long distance relationship can be expensive, especially if you travel often to see your partner.   If your partner is waiting for a controlling parent to "back off," that means neither of you have any control over the date. Similarly, if you are waiting for a job to open up in your partner's city, you may be stuck waiting with no date in sight. To avoid this, agree on a date by which you will either move (with or without the job) or break up. For instance, you might say "I'll move to your city as soon as I find a job there. However, if I haven't found one in the next six months, I'll just move and take my chances." However, make sure that you have a conversation about finances before doing something like this to make sure that one partner is able to support the other as they look for a job. If you are planning to be in a perpetually distant relationship, make sure you are both okay with that. You should both feel comfortable with the amount of texting, calling, emailing, and visiting you do. Ask your partner if they feel you're at the right level, and ask yourself how you feel as well.  If you find that one of you is feeling neglected or inundated, agree on a different schedule together. If it feels like only one of you is willing to compromise, your relationship might not be working. You should still be able to hang out with friends, visit family, go to parties, and have time to yourself. If you feel like your long distance relationship is making it impossible for you to have a social life where you are, you need to draw some boundaries.  Tell your partner you can't visit them as frequently. Explain that you are feeling lonely from never making any friends where you are. Explain to your partner that you will schedule a certain amount of time to talk to them, but that you can't be on call constantly. If your partner freaks out or refuses, your relationship might not be working. Do you know the terms of your relationship? Does your partner? Ask yourself what you expect, then make this clear to your partner and ask what they expect as well.  For instance, if you believe that you and your partner are monogamous, in love, and heading toward living together in the next few years, tell your partner! Similarly, if you believe you and your partner are in an open relationship, you'll need to define those terms as well. Being distant means communicating more, not less, so make an effort to get on the same page. If your partner wants to "keep it loose," that means they aren't willing to be open with you about their expectations. That's a bad sign.
Question: What is a summary of what this article is about?
Decide how long you can handle being in a long distance relationship. Keep a communication schedule that works for both of you. Make sure you can both maintain a social life. Clarify your expectations.