Confusing calculator result

I was doing some simple maths for a project when I stumbled upon an error (?) in my calculator (casio fx 991), I'll explain:

I wanted to make the next rule of three calculation:

$$\frac{x}{4}=\frac{0.74}{1.7} \longrightarrow x=\frac{0.74 \cdot 4}{1.7}$$

by putting $$0.74 \cdot 4$$ on the calculator, it equals to $$2.96$$, by now it is correct.

then, I press $$\texttt{Ans} \div 1.7$$ and it gives me $$1.024...$$ as result.

when putting this result back on the first equation, something doesn't feels right.

$$\frac{1.024}{4}=\frac{0.74}{1.7}$$

then, I used the Symbolab website to make sure it was right, and it was wrong, I found out $$x$$ should be equal to $$1.74$$.

what is the problem here? is it something about how calculators work? i am sure i didn't commited a mistake.

• There is something wrong here ' i press Ans÷1.7 and it gives me 1.024... as result' Jun 2, 2021 at 23:36
• Clearly, $\frac {2.96}{1.7}\neq 1.024$
– lulu
Jun 2, 2021 at 23:37
• You somehow divided twice 2.96 / 1.7 / 1.7 ≈ 1.024.
– dxiv
Jun 2, 2021 at 23:38
• Seems there's another previous calculus whose result is 1.74, so Ans used it Jun 2, 2021 at 23:38

2 Answers

Each of the steps you did was correct, until you divided by $$1.7$$. If you divide by $$2.96$$ by $$1.7$$ once, you get $$1.74$$ as expected. The problem was you divided by $$1.7$$ twice (as dxiv mentioned in the comments above), giving you $$1.024$$.

• now i see it, it was because it gave a fracctional answer first and i wanted it in decimals, i pressed shift+= and it counted with the last answer. Thank you and dxiv. Jun 2, 2021 at 23:56

I think you may have pressed = twice in a row

Mine hidden in a cupboard takes 0.74 × 4 = and gives $$\frac{74}{25}$$ which is indeed $$2.96$$. (How do you turn fractions off?)

Then doing Ans ÷ 1.7 = gives $$\frac{148}{85}$$ which is $$1.741176471$$

But pressing = again gives $$\frac{296}{289}$$ which is $$1.024221453$$ as it repeats the division by $$1.7$$.