1) An approximation is an inexact representation of something that is still close enough to be useful as it may yield an accurate solution while reducing complexity. 2) Significant figures include certain digits that are accurate and one uncertain digit that has some error possibility. 3) When adding and subtracting numbers, the final result should be rounded to the same precision as the least precise initial value. When multiplying, dividing, or taking roots the result should have the same number of significant figures as the least precise number.