A day has 24 hours. We use clocks to measure hours during the day. The day starts at midnight (12:00 am) and ends at the next midnight.

For example:

• From 6:00 am to 6:00 pm is 12 hours (daytime)
• From 6:00 pm to 6:00 am is 12 hours (nighttime)
• Together, they make 24 hours in one day

A week has 7 days. The days of the week are:

• Monday
• Tuesday
• Wednesday
• Thursday
• Friday
• Saturday
• Sunday

Example: If today is Monday, then tomorrow is Tuesday. After 7 days from Monday, it will be Monday again.

A month has 4 weeks.

Example: If a month has 28 days, it has exactly 4 weeks (7 × 4 = 28).

However, note that a month can have 28, 29, 30 or 31 days. This means some months have a little more than 4 weeks.

A year has 12 months. The months are:

Tip: Thirty days have September, April, June and November. All the rest have thirty-one, except February alone which has twenty-eight days clear, and twenty-nine in each leap year.

• 1 day = 24 hours
• 1 week = 7 days
• 1 month = 4 weeks (approximately)
• 1 year = 12 months

Example 1: How many days are there in 3 weeks?

Solution: 1 week = 7 days
3 weeks = 3 × 7 = 21 days

Example 2: Bakari bought airtime that lasted for 48 hours. How many days is that?

Solution: 1 day = 24 hours
48 hours = 48 ÷ 24 = 2 days

Example 3: How many months are there in 2 years?

Solution: 1 year = 12 months
2 years = 2 × 12 = 24 months

In Tanzania, knowing the number of hours in a day, days in a week, weeks in a month, and months in a year helps us plan daily activities. For example, a shopkeeper in Dar es Salaam uses a calendar to know which day of the week market day falls on, or to count how many days until a festival like Eid al-Fitr or Christmas. A farmer also uses these time relationships to know when to plant crops according to seasons and months of the year.