Difficulty: Moderately Easy
Things You’ll Need:
Step1
Write legibly! This sounds too obvious, but many stupid mistakes result from students misreading their own handwriting. For example, flat 9's can look like 7's, 4's can look like 9's. Sloppy 6's can look like sloppy 0's.
Step2
Estimate your answer before you start. If you are doing a problem that contains decimals, this is very important. For example, if your problem is 2.3 times 2.2, round them off and think of the problem as 2 times 2. You should get something close to 4. If your answer is 50.6, that’s nowhere close to 4 and you should check your decimal point. If your answer is 5.06, 5 is pretty close to 4; so your answer is likely correct.
Step3
Use graph paper. Many stupid mistakes result from getting numbers in the wrong place value columns. Using graph paper will make sure your columns stay straight. Graph paper is especially helpful for long division, as it will make sure you don’t omit numbers in the quotient.
Step4
Talk to yourself inside your head. This may sound silly, but it can be an immense help, especially when setting up problems. For instance, when you are turning fractions into decimals you need to make sure to get the top number (numerator) inside the “house” (long division symbol) and the bottom number (denominator) outside it. Switching these is a common error. To avoid this error, say the fraction as you write the division. For instance, if you are dividing 1/3, say “1” and write a “1,” then say “divided by” and draw the division “house” over the “1,” then say “3” and write a “3” outside the “house.”
Step5
Watch those signs. Many students add when they are supposed to subtract and vice versa, just because they don’t look carefully at the signs. If you have a page of mixed practice problems, make sure to look at the sign and make sure you do what it says.
Step6
Re-read the questions after you think you have the answer. Does your answer actually answer the question? Watch out for two and three step problems. You may have done just the first step and write it down as the answer. Here is an example: “If the store is having a 10 percent off sale and the item is $9.95, how much do you pay?” If you simply calculate 10 percent of 9.95 and write down “.99” your answer will be wrong. You must go on to subtract that .99 from 9.95 to get $8.96. If you had re-read the question and were reminded that they wanted to know how much you paid, 99 cents would obviously be too small a number.
Step7
After doing a subtraction problem, check it by doing addition from the bottom up. Imagine it as an upside-down addition problem and add the bottom line (your answer) to the line above it and you should get the number on the top line.
Novice 
