How is estimation when adding and subtracting decimals?

Estimation is always helpful when it comes to math. By estimating, you will have a good idea with what the final answer should be before you actually get it. This way, you will hopefully be able to have a good sense of whether the answer is wrong

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.