估算简便快捷。

(1) $527-218 \approx$

(2) $799-201 \approx$

(3) $108+349 \approx$

(4) $603+188 \approx$
(1) $527-218 \approx 310$

(2) $799-201 \approx 600$

(3) $108+349 \approx 460$

(4) $603+188 \approx 790$