## Units of time

1 min (minute) = 60 s (seconds)

1 h (hour) = 60 min
600

1.5 h = $1{1/2}$h = 1 h 30 min

1 h = 60 × 60 s= 3600 s

Math Tests - mathematics practice questions

Convert units of time (seconds and minutes)

1 min (minute) = 60 s (seconds)

1 h (hour) = 60 min
600

1.5 h = $1{1/2}$h = 1 h 30 min

1 h = 60 × 60 s= 3600 s

Convert units of time (seconds, minutes and hours)

1 min (minute) = 60 s (seconds)

1 h (hour) = 60 min
600

1.5 h = $1{1/2}$h = 1 h 30 min

1 h = 60 × 60 s= 3600 s

Convert units of time (weeks, months, years)

1 min (minute) = 60 s (seconds)

1 h (hour) = 60 min
600

1.5 h = $1{1/2}$h = 1 h 30 min

1 h = 60 × 60 s= 3600 s

**day** = 24 h
**week** = 7 days

**month** = 28/29 days (February) or 30 days (April, Jun, September, November) or 31 days (January, March, May, July, August, October, December)
**year** = 12 months = 365 days = 52 weeks 1 day
**leap year** = 12 months = 366 days = 52 weeks 2 days

A **leap year** is a year in which an extra day is added to the calendar in order to synchronize it with the seasons. In leap years, February 29th is added as leap day, which doesn't exist in a normal year (February has normally 28 days).
A leap year occurs every 4 years - the year has to be evenly divided by 4 (

Convert metric units of length (cm, dm, m)

m... meter

dm... decimeter

cm... centimeter

1 m = 100 cm = 10 dm

1 dm = 10 cm 572

Convert metric units of length (easy)

1 cm (centimeter) = 10 mm (milimeter)

1 dm (decimeter) = 10 cm

1 m (meter) = 100 cm = 10 dm

1 km (kilometer)= 1000 m 567

Convert metric units of length (medium)

1 cm (centimeter) = 10 mm (milimeter)

1 dm (decimeter) = 10 cm

1 m (meter) = 100 cm = 10 dm

1 km (kilometer)= 1000 m 567

Convert metric units of length (difficult)

1 cm (centimeter) = 10 mm (milimeter)

1 dm (decimeter) = 10 cm

1 m (meter) = 100 cm = 10 dm

1 km (kilometer)= 1000 m 567

Convert and compare US units of length (inches, feet, yards)

1 inch (in) ≅ 2.54 centimeters (cm)

1 foot (ft or ′) = 12 in ≅ 30.48 cm

1 yard (yd) = 3 ft = 36 in ≅ 0.91 meter (m)

1 mile (mi)= 1760 yd ≅ 1.6 kilometer (km)

Convert metric units of area

1 cm^{2} = 10 mm × 10 mm = 100 mm^{2}

1 dm^{2} = 10 cm × 10 cm = 100 cm^{2}

1 m^{2} = 10 dm × 10 dm = 100 dm^{2} = = 10000 cm^{2}

1 km^{2} = 1000 m × 1000 m = 1000000 m^{2}

Convert and compare units of mass (kg and g)

1 g (gram) = 1000 mg (milligram)

1 kg (kilogram)= 1000 g

1 t (ton) = 1000 kg

1 dkg (dekagram) =10 g

1 kg (kilogram)= 1000 g = 100 dkg

Convert and compare US units of mass (ounces and pounds)

1 pound (lb) = 16 ounces (oz) ≅ 0.45 kilogram (kg)

1 oz ≅ 28 grams (g)

1.5 lb = 16 + 8 = 24 oz

$1/2$ lb = 8 oz

Convert metric units of speed/velocity

Velocity is measured as distance traveled per certain unit of time, e.g. if car drives 40 km/h, that means that a car drives 40 km every hour (40 km in one hour, 80 in two hours, 120 in three hours. etc.). The American equivalent is mph (miles per hour). Since this is a combination of units (distance divided by time), when recalculating to different units of velocity we need to pay attention to both units (time and distance), and determine how to change them.

If we are moving 2 m/s, it means that every second we travel 2 meters. How many meters will we travel in one hour? One hour has 3600 seconds.

$$2;m/s=$$

$$=2×3600=7200;m/s$$

In one hour we will travel 7200 m. And how many kilometers will we move in 1 hour? We know that 1 km is equal to 1000 m.

$$ 7200;m/s=7.2;km/s $$

If a car is moving 90 km/h, how many meters per second will it drive? In this case we have to multiply 90 by 1000 to calculate the meters (90 km=90000 m). At the same time we have to divide the value by 3600 since one hour has 3600 seconds:

$$90;km/h={90000;m}/{3600;s}=25;m/s$$

So the car is driving 25 m/s. But what is his speed in km/min? As we know, 1 hour has 60 minutes. It means that in one minute it will drive:

$$90;km/h=$$

$$={90;km}/{60;min}=1.5;km/min$$

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