Glossary — Number
Decimal place — a position after the decimal point; the first is tenths, the second hundredths.
Estimate — a quick, approximate answer found by rounding, used to check whether an exact answer is reasonable.
Index (plural indices) — a power, such as the in .
Integer — a whole number, positive, negative or zero.
Inverse operation — the operation that undoes another; addition and subtraction are inverses, as are multiplication and division.
Loss — a negative profit: the money taken is less than the money spent.
Negative number — a number less than zero, written with a minus sign.
Order of operations — the convention (BIDMAS) for the order in which operations are carried out: brackets, indices, division and multiplication, addition and subtraction.
Place value — the value a digit has because of its position in a number.
Profit — money left after costs are subtracted from the money taken.
Reciprocal — the result of dividing 1 by a number; the reciprocal of is .
Rounding — replacing a number by a nearby number with fewer significant figures or decimal places.
Significant figures — the digits that carry meaning in a number, counted from the first non-zero digit.