Arithmetic · real student question

Evaluate 10^-2.

Question

Evaluate

10210^{-2}

Step-by-step solution

  1. Apply the negative-exponent definition. A negative exponent signals a reciprocal, never a negative result:

    an=1an102=1102a^{-n}=\frac{1}{a^{n}}\qquad\Longrightarrow\qquad10^{-2}=\frac{1}{10^{2}}

    The commonest misreading is treating 10210^{-2} as 100-100 or 20-20. The base stays positive; only its position moves, from numerator to denominator.

  2. Evaluate the positive power.

    102=10×10=10010^{2}=10\times10=100

  3. Write the fraction and the decimal.

    102=1100=0.0110^{-2}=\frac{1}{100}=0.01

    The exponent 2-2 moves the decimal point two places left from 11, which is the fast way to read any power of ten.

  4. Check against the pattern of powers of ten. Reading downward, each step divides by 1010:

    102=100,101=10,100=1,101=0.1,102=0.0110^{2}=100,\quad10^{1}=10,\quad10^{0}=1,\quad10^{-1}=0.1,\quad10^{-2}=0.01

    The sequence continues smoothly through zero and into negatives ✓, which is exactly the reason negative exponents are defined this way.

  5. Confirm with the exponent laws. Multiplying by the positive power should return 11:

    102×102=102+2=100=110^{-2}\times10^{2}=10^{-2+2}=10^{0}=1

    and indeed 0.01×100=10.01\times100=1 ✓. In scientific notation 10210^{-2} is the multiplier for centi, which is why 11 cm =102=10^{-2} m.

Answer

102=1100=0.0110^{-2}=\frac{1}{100}=0.01

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