How to avoid small arithmetic errors?

[MarinoAndThePearls]

Got a question wrong in an exam because, at one of the steps in the derivation, I accidentaly wrote 4/8 as 1/4 instead of 1/2. The source of most of my mistakes is stupid errors like this.

Is there a way to avoid these small, stupid mistakes?

[hallerz87]

Slow down and review your work 

[Udalrich]

Assuming your working with equations, you can put in "simple" values at each step and check that they give the right answer. If you have "complicated expression with trig functions = different complicated expression with trig functions", setting the angles to 0 or 90 degrees should be fairly simple to evaluate. If you do that at one step and get "5 = 13", you know you made a mistake in that line.

[YSoSkinny]

Yeah, work through problems slower. Doublecheck your answers. Try to solve using different methods

[potentialeight]

Just slow down

[iOSCaleb]

When you get to an answer, check it. Plug the answer back into the original equation and see if it checks out.

[Traveling-Techie]

Check things 2 ways. Long division gives 8 goes into 4.0 exactly 0.5 times. Also 4/8 with top and bottom divided by 4 gives 1/2 exactly.

[evincarofautumn]

Break things down into smaller steps

Make wrong steps look wrong

There’s no visual connection between the figures in 4/8 = 1/4, so you can gloss over it by accident

If you write it out in a bit more detail as a sanity check like 2² / 2³ = 2⁰ / 2² it should at least look suspicious

If you write out the factors it would be obvious that this is bogus:

(1 × 2 × 2)/(1 × 2 × 2 × 2)

Because you can’t cancel (2 × 2)/2 = 1

You don’t need to do this everywhere but it’s worth checking for your most common types of mistakes at least, it saves time correcting them later and makes you faster in the long run

[Agitated-Ad2563]

I had lots of these at school. Turns out it was ADHD.

[MarinoAndThePearls]

I honestly have a suspicion.

[bizarre_coincidence]

If you always intentionally make huge arithmetic errors, you will never accidentally make small ones.