Answer:
Two
Step-by-step explanation:
In <em>multiplication problems</em>, your answer can have no more significant figures than the number with the <em>fewest significant figures</em>.
Start with the calculation inside parentheses:
5.1 × 10.6 = 54.060 000 00 (by my calculator)
There are three significant figures in 10.6, but only two in 5.1.
In this were a number you had to report, you would round to <em>two</em> significant figures and report the answer as 54.
54.060 000 00 → 54 (to two significant figures)
However, you must multiply this intermediate answer by 2.524.
Therefore, you multiply the number in the calculator by 2.524 and get
54.060 000 00 × 2.524 = 136.447 4400
<em>NOW</em>, you round to two significant figures and report the answer as <em>140</em>.