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An exponent, also called a power or index, [1] is a number that tells you how much to multiply a base number. To solve an addition sentence that includes exponents, you must know how to find the value of the individual exponential expressions, either by hand or by using a calculator . When adding variables with exponents, you must be aware of certain rules for combining like terms.

Method 1
Method 1 of 3:

Adding Numbers With Exponents By Hand

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  1. An exponential expression has a base (large number) and exponent (small number). The exponent tells you how many times to multiply the base by itself ( ). [2]
    • For example, if your problem is , you would first calculate :


  2. To do this, multiply the base by itself the number of times indicated by the exponent.
    • For example, the problem is now , so you need to calculate :


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  3. This will give you the sum of the two exponential expressions.
    • For example:



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Method 2
Method 2 of 3:

Adding Numbers With Exponents Using a Calculator

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  1. This key will likely look like or , or it may look like an with a blank box as the exponent. If you do not have a scientific calculator, you cannot use this method.
  2. To do this, hit the base number (large number) first, then hit the exponent.
    • For example, if your problem is , you would hit the following sequence of keys to solve the first expression:


  3. This will show you the value of the first exponential expression. You do not need to hit the equal key ( ) after typing in the first exponential expression.
    • For example, after typing in the expression , you should hit the symbol to see a value of .
  4. To do this, hit the base number (large number) first, then hit the exponent.
    • For example, if your problem is , you would hit the following sequence of keys to solve the second expression:


  5. This will show you the final sum of the two exponential expressions.
    • For example, after hitting the appropriate sequence of keys, adds up to .
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Method 3
Method 3 of 3:

Adding Variables With Exponents

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  1. The base is the large number (or variable) in the exponential expression, and the exponent is the small number.
    • The exponent tells you how many times to multiply the base by itself ( ). [3]
    • In the case of variables, an exponential expression will also have a coefficient, which is a number appearing before the variable that tells you how to multiply the variable. [4]
    • Even if a variable has no coefficient, it is understood to have the coefficient of . For example,
  2. [5] When working with variables, there is no way to add terms that do not have the same base and the same exponent. The terms must have BOTH of these parts in common.
    • For example, if the problem is , you should note that and have the same base ( ) and the same exponent ( ). Thus, these two terms can be added together. The term has a different exponent, so it cannot be added; the term has a different base, so it cannot be added.
  3. Remember, if a term has no coefficient shown, a coefficient of is understood. Do NOT add the exponents. The exponent stays the same.
    • For example, if you are calculating you would add together the coefficients, and would stay the same:


  4. Remember, you cannot add exponential expressions that do not have the same base AND exponent, so those will stay the same as they were in the original problem.
    • For example, simplifies to .
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Community Q&A

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  • Question
    What is x cubed plus x cubed?
    Community Answer
    Since the two expressions have the same base (x) and the same variable (3), you can just add the coefficients. If a variable has no coefficient, it really has a coefficient of 1. The exponents will stay the same. So: x^3 + x^3 (1)x^3 + (1)x^3 2x^3
  • Question
    How do I add x to the power of 2 plus 4x?
    Community Answer
    The exponents are not same, therefore it is impossible to add it.
  • Question
    How do figure out what X squared plus X to the negative 2 is?
    Community Answer
    X^2 +X^-2. It cancels itself because ^2 and ^-2 are opposites. That makes X raised to the 1st. X^1 is X.
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      About This Article

      Article Summary X

      To add exponents, start by solving the first exponential expression in the problem by multiplying the base number by itself the number of times shown in the exponent. For example, to solve for 3 to the fourth power, you would multiply 3 by 3 by 3 by 3 to get 81. Then, solve the second expression in the same way. Finally, add the two values together to get the sum of the 2 exponential expressions. For tips on how to add variables with exponents, read on!

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