Mathematical tables containing common logarithms (base-10) were extensively used in computations prior to the advent of computers and calculators, not only because logarithms convert problems of multiplication and division into much easier addition and subtraction problems, but for an additional property that is unique to base-10 and proves useful: Any positive number can be expressed as the product of a number from the interval  and an integer power of  This can be envisioned as shifting the decimal separator of the given number to the left yielding a positive, and to the right yielding a negative exponent of  Only the logarithms of these normalized numbers (approximated by a certain number of digits), which are called mantissas, need to be tabulated in lists to a similar precision (a similar number of digits). These mantissas are all positive and enclosed in the interval . The common logarithm of any given positive number is then obtained by adding its mantissa to the common logarithm of the second factor.
Mathematical tables containing common logarithms (base-10) were extensively used in computations before computers and calculators, not only because logarithms simplify multiplication and division into easier addition and subtraction problems, but also due to a unique property that is specific to base-10 and useful: Any positive number can be expressed as the product of a number from the interval  and an integer power of . This can be imagined by moving the decimal point of the given number to the left for a positive exponent or to the right for a negative exponent. Only the logarithms of these normalized numbers (approximated by a certain number of digits), known as mantissas, need to be tabulated in lists with similar precision. These mantissas are all positive and fall within the interval . The common logarithm of any given positive number is then found by adding its mantissa to the common logarithm of the second factor.