MathematicsClass 8Exponents and Powers

Comparing Very Large and Very Small Numbers

Utilizing standard form representations to compare magnitudes of extreme values.

Class 8 · MathematicsCBSE & ICSE SOF IMO

Definition

Comparing very large and very small numbers involves analyzing their scale using exponents or standard form rather than standard counting. By converting numbers to standard form with powers of 10, we can easily determine which number is greater by looking at the exponent values. If the exponents are equal, we compare the decimal coefficients.

Key formula

Compare a \times 10^m and b \times 10^n by comparing exponents m and n

Worked examples

1

Compare 3 \times 10^7 and 4 \times 10^5; since 7 > 5, the first number is much larger.

2

Compare 1.5 \times 10^{-4} and 2.5 \times 10^{-4}; since exponents are equal, 2.5 is greater than 1.5, so the second number is larger.

3

Determine which is larger between 500,000 (5 \times 10^5) and 0.00005 (5 \times 10^{-5}) by noting that a positive exponent is always larger than a negative one.

Common mistakes

  • Looking only at the decimal coefficient while ignoring the power of 10, incorrectly concluding that 9 \times 10^2 is larger than 1 \times 10^6.
  • Misinterpreting negative exponents, thinking that a more negative exponent like -10 represents a larger value than a less negative exponent like -3.
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