Upper and Lower Bounds

Question 1:

When x = 59 (2 s.f.) and
y = 800 (1 s.f.), find the upper bound of x + y

909.5

Question 2:

When x = 0.452 (3 d.p.) and
y = 0.21 (3 d.p.), find the upper bound of x - y

0.243

Question 3:

When x = 0.088 (3 d.p.) and
y = 0.98 (2 d.p.), find the lower bound of x × y

0.0853125

Question 4:

When x = 8000 (1 s.f.) and
y = 9 (1 s.f.), find the upper bound of x ÷ y

1000