Final answer:
To round the number 42.598 to 2 significant figures, we look at the third digit after the decimal point. Since it is 8, which is greater than 5, we round up the last significant figure to get 42.60.
Step-by-step explanation:
To round a number to 2 significant figures, we look at the digit in the 3rd place after the decimal point. If it's 5 or greater, we round up the last significant figure. If it's less than 5, we leave the last significant figure as it is. In the case of 42.598, the digit in the 3rd place after the decimal point is 8, which is greater than 5. Therefore, we round up the last significant figure, which is 9, resulting in the rounded value of 42.60.