61
Practical tasks (continued)
Textbook: Part 2, lesson 61, pp. 69–71
GoalPractical tasks with time units, leap years and Roman numerals.
New words
leap year · kabisa yiliday (24 hours) · sutkaweek · haftaRoman numerals · Rim raqamlari
Explanation
1 year = 365 days, a leap year has 366. 1 week = 7 days, 1 day = 24 hours, 1 hour = 60 minutes, 1 minute = 60 seconds. Leap-year rule: a year divisible by 4 is a leap year; but a year divisible by 100 is not; a year divisible by 400 is a leap year again. Roman numerals: I = 1, V = 5, X = 10, L = 50, C = 100; a smaller numeral before a bigger one is subtracted (IX = 9, XC = 90).
Worked examples
2024 : 4 = 506 – a leap year. 1900 is divisible by 100 but not by 400 – an ordinary year. 2000 is divisible by 400 – a leap year.
LXIX = L + X + IX = 50 + 10 + 9 = 69.
Class activity
“Leap-year detectives”: each child gets a card with a year. Using the rule, children sort themselves into “leap” and “ordinary” groups.
Practice
1
How many seconds are in 1 hour?
3600
2
How many hours are in 1 week?
168
3
How many hours are in a leap year?
8784
4
Is the year 2100 a leap year?
No: it is divisible by 100 but not by 400
5
How many minutes is 4 hours 10 minutes?
250
6
Write the Roman numeral LXIX in Arabic numerals.
69