Final answer:
Signed numbers in math have either a positive (+) or negative (-) sign, indicating their position relative to zero. When performing operations, these signs determine the result's sign, with rules for addition, subtraction, multiplication, and division. Exact numbers, obtained by counting or definitions, have infinitely many significant figures.
Step-by-step explanation:
Signed numbers in mathematics refer to numbers that have a sign (either + or -) to the left of them, indicating their position relative to zero on the number line. The sign of a number helps us understand its value in equations and calculations. A positive sign (+) implies the number is greater than zero, while a negative sign (-) indicates the number is less than zero. If no sign is indicated, it is conventionally understood to be positive.
Let's look at how the sign affects common mathematical operations:
- When adding or subtracting signed numbers, like -5 + 3, you subtract the smaller number from the larger one and give the result the sign of the larger number, resulting in -2 in this case.
- When multiplying or dividing signed numbers, the sign rules are cohesive. Multiplying two positive numbers or two negative numbers will give a positive result, for instance, 2 x 3 = 6, and (-4) x (-3) = 12. However, if the signs differ, as in (-3) x 2, the result will be negative: -6.