Final answer:
12/17 as a decimal, rounded to the nearest thousandth, is 0.706, obtained by dividing 12 by 17 and rounding up due to the fourth decimal place being greater than 5.
Step-by-step explanation:
To convert the fraction 12/17 to a decimal, divide 12 by 17. Upon doing this calculation, we get approximately 0.7058823529411765. Now, to round this to the nearest thousandth, we look at the fourth decimal place, which in this case is an '8'. Therefore, we round up the third decimal place from '5' to '6', giving us 0.706 as the final answer, rounded to the nearest thousandth.