Here are some rough metric/imperial equivalents that you should learn.

3 ft is approximately 1 m

5 miles is approximately 8 km

2 lbs is approximately 1 kg

1 oz is approximately 30 g

2 pints is approximately 1 litre

__Example 1__

Approximately how many grams are equivalent to 4 oz.

__Answer__

1 oz = 30g

4 oz = 4 × 30 = **120** g

__Example 2__

Approximately how many km are equivalent to 100 miles.

__Answer__

5 miles = 8 km

100 miles = **160** km (multiply each side by 20)