Answer
a. $641.0$
b. $1.327$
c $77.34$
d. $3215$
e. $0.420$
Work Step by Step
a. $$\begin{aligned}
&212.2 + 26.7+ 402.09\\
&=238.9+ 402.09\\
&=640.99
\end{aligned}$$ The limiting figures ($212.2$ and $26.7$) have one decimal place.
Answer $=641.0$
b. $$\begin{aligned}
&1.0028 +0.221+0.10337\\
&=1.2238+0.10337\\
&=1.32717
\end{aligned}$$ The limiting figure ($0.221$) has three decimal places.
Answer $=1.327$
c. $$\begin{aligned}
&52.331 +26.01-0.9981\\
&=78.341-0.9981\\
&=77.3429
\end{aligned}$$ The limiting figure($26.01$) has two decimal places.
Answer $=77.34$
d. $$\begin{aligned}
&2.01 \times10^2 +3.014 \times 10^3\\
&=201 + 3014\\
&=3215
\end{aligned}$$ Answer $=3215$
e. $$\begin{aligned}
&7.255-6.8350\\
&=0.420
\end{aligned}$$ The limiting figure ($7.255$) has three decimal places.
Answer $=0.420$
