Exponents are a concise way to show that a number (the base) is multiplied by itself several times.

a0 = 1 for any nonzero a.
a1 = a.
Note: the expression 00 is indeterminate in many contexts; the GMAT does not test 00.
If n > 0 then 0n = 0.
If n < 0 then 0n is undefined (division by zero would be implied).
1n = 1 for any integer n.
a-n = 1 / an for a ≠ 0.
Important: 0 cannot be raised to a negative power because that requires division by zero; for example 0-1 is undefined.

(-1)n = 1 if n is even, and (-1)n = -1 if n is odd.
If two factors have the same exponent, multiply or divide the bases and keep the common exponent:
(ab)n = an bn

When multiplying with the same base, keep the base and add exponents: am · an = am+n.
When dividing with the same base, keep the base and subtract exponents: am / an = am-n.

(am)n = am·n.
ap/q = q√(ap) = (q√a)p where q > 0 (principal qth root).

Try yourself: The value of 2-2 is:
Roots (radicals) reverse the action of exponents. For example, if x2 = 16 then √16 = 4 (principal square root).

√[q]{a} = a1/q. In particular, √a = a1/2.
q√(ab) = q√a · q√b for non-negative a and b when q is even; the property extends for principal roots where defined.
q√(am) = (q√a)m = am/q.

Try yourself: 22 x 23 x 24 is equal to:
Simplify the following expressions by combining like terms. If the base is a number, leave the answer in exponential form (for example, write 23 rather than 8).
Ques 1. x5 x x3
Ans:
x5 x x3 =
x5+3 =
x8
Ques 2: 76 x 79
Ans:
76 x 79 =
76+9 =
715
Ques 3: 55/55
Ans:
55 / 55 =
55-5 =
50 =
1
Ques 4: (a3)2
Ans:
(a3)2 =
a3·2 =
a6
Ques 5: 4-2 x 45
Ans:
4-2 x 45 =
4-2+5 =
43
Ques 6: (-3)a/ (-3)2
Ans:
(-3)a / (-3)2 =
(-3)a-2
Ques 7: (3)2-3
Ans:
32-3 =
3-1
Ques 8: 114/11x
Ans:
114 / 11x =
114-x
Ques 9: x2 x x3 x x5
Ans:
x2 x x3 x x5 =
x2+3+5 =
x10
Ques 10: (52)x
Ans:
(52)x =
52x
Ques 11: 34 x 32 x 3
Ans:
34 x 32 x 3 =
34+2+1 =
37
Ques 12: x5 x x6 / x2
Ans:
x5 x x6 / x2 =
x5+6-2 =
x9
Ques 13: 56 x 54x / 54
Ans:
56 x 54x / 54 =
56+4x-4 =
54x+2
Ques 14: y7 x y8 x y-6
Ans:
y7 x y8 x y-6 =
y7+8+(-6) =
y9
Ques 15: x4/x-3
Ans:
x4 / x-3 =
x4-(-3) =
x7
Ques 16: z5 x z-3 / z-8
Ans:
z5 x z-3 / z-8 =
z5+(-3)-(-8) =
z10
Ques 17: 32x x 36x / 3-3y
Ans:
32x x 36x / 3-3y =
32x+6x-(-3y) =
38x+3y
Ques 18: (x2)6 x x3
Ans:
(x2)6 x x3 =
x2·6 x x3 =
x12+3 =
x15
Ques 19: (z6)x x z3x
Ans:
(z6)x x z3x =
z6x x z3x =
z6x+3x =
z9x
Ques 20: 53 x (54)y / (5y)3
Ans:
(54)y = 54y and (5y)3 = 53y.
Therefore, 53 x 54y / 53y =
53+4y-3y =
5y+3
Ques 21: Compute the sum.

Ans:

We need the smallest (lowest) numerical value. Positive numbers are greater than any negative number, so consider only negative options.
(A) (-3)4 is positive because the exponent is even.
(B) -33 = -(33) = -27.
(C) (-3)-3 = 1 / (-3)3 = -1/27 (negative but ~ -0.037).
(D) (-2)3 = -8.
(E) 2-6 = 1 / 64 (positive).
Compare the negative values: -27, -8, and -1/27. The smallest is -27. Thus the correct answer is (B).


Ques 23: Compute the sum.

Ans:

The first two terms are equal and cancel when one is subtracted from the other, leaving only the third term.
Ques 24: Which of the following is equal to (2/5)-3?


Ans:

The correct answer is (E).
Note: when simplifying, check choices to avoid over-manipulation.
Ques 25: Which of the following has a value less than 1? (Select all that apply)


Ans:

Dividing a smaller positive number by a larger positive number gives a value between 0 and 1.

Dividing a larger positive number by a smaller positive number gives a value greater than 1.

This expression is negative, so it is less than 1.

Dividing a larger positive number by a smaller positive number gives a value greater than 1.
(E) (-4)3 = -64, which is negative and therefore less than 1.
Simplify the following expressions by finding common bases.
Ques 26: 83 x 26
Ans:
8 = 23, so 83 = (23)3 = 29.
Then 29 x 26 = 215.
Ques 27: 492 x 77
Ans:
49 = 72, so 492 = (72)2 = 74.
74 x 77 = 711.
Ques 28: 254 x 1253
Ans:
25 = 52 so 254 = 58.
125 = 53 so 1253 = 59.
58 x 59 = 517.
Ques 29: 9-2 x 272
Ans:
9 = 32, so 9-2 = (32)-2 = 3-4.
27 = 33, so 272 = 36.
3-4 x 36 = 32.
Simplify the following expressions by pulling out common factors.
Ques 31: 63 + 33 = (A) 35 (B) 39 (C) 2(33)
Ans:
6 = 2 x 3, so 63 = (2 x 3)3 = 23 x 33.
63 + 33 = 23 x 33 + 33.
Factor 33: 33(23 + 1) = 33(8 + 1) = 33 x 9 = 33 x 32 = 35.
Answer: A.
Ques 32: 813 + 274 = (A) 37(2) (B) 312(2) (C) 314
Ans:
81 = 34, so 813 = (34)3 = 312.
27 = 33, so 274 = (33)4 = 312.
312 + 312 = 312(1 + 1) = 2 · 312.
Answer: B.
Ques 33: 152 - 52 = (A) 52(2) (B) 5223 (C) 5232
Ans:
15 = 3 x 5, so 152 = (3 x 5)2 = 32 x 52.
152 - 52 = 32 x 52 - 52 = 52(32 - 1) = 52(9 - 1) = 52 x 8 = 52 x 23.
Answer: B.
Ques 34:

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Ques 35:

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Ques 36:

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Ques 37:

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Ques 38:

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Ques 39:

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Ques 40:

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Ques 41:

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Ques 42:

Ans:

Simplify the following roots. Not every answer will be an integer.
Ques 43: √32
Ans:

Ques 44: √24
Ans:

Ques 45: √180
Ans:

Ques 46: √490
Ans:

Ques 47: √450
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Ques 48: √135
Ans:

Ques 49: √224
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Ques 50: √343
Ans:

Simplify the following roots. You will be able to completely eliminate the root in every question. Express answers as integers.
Ques 51:

Ans:
Pull out the greatest common perfect square factor of the terms under the square root.

Both 32 and 169 are perfect squares (169 = 132), so

Ques 52:

Ans:
Pull out the greatest common perfect square factor of the terms under the square root.

Both 72 and 16 are perfect squares (16 = 42), so

Ques 53:

Ans:
Pull out the greatest common perfect square factor of the terms under the square root, namely 56.

56 and the remaining factor are perfect squares, so

Ques 54:

Ans:
Pull out the greatest common perfect square factor 84.

Both 84 and 32 are perfect squares, so

Ques 55:

Ans:
Pull out the greatest common perfect square factor 212, leaving perfect-square factors in both parts.

212 and 32 are perfect squares (212 = 26 x 26), so

Ques 56:

Ans:
Pull out the greatest common perfect square factor 502.

Both 502 and 72 are perfect squares, so

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