How_To_Be_Good_At_Math

MEASUREMENT • DATES MEASUREMENT • DATES 195

January

1 2 3

4 5 6 7 8 9 10

11 12 13 14 15 16 17

18 19 20 21 22 23 24

25 26 27 28

M T W T F S S

29 30 31

February

1 2 3 4 5 6 7

8 9 10 11 12 13 14

M WT T F S S

Calendars

We use calendars to arrange all the days in a year

into months and weeks. They help us to measure

and keep track of the passing of time.

The 365 days in a year don’t fit neatly into a

perfect number of weeks or months, so the

day of the week that a month begins and ends on

changes each year.

Here, January starts on a Friday and ends on

a Sunday. This means that the previous month,

December, ended on a Thursday and the next

month, February, will begin on a Monday.

In following years, January will begin and end

on different days of the week.

So, we can refer to the last day in January on

this calendar as Sunday 31 January.

Look at this calendar showing the month

of January.

When we want to refer to a specific day in the

year, or date, we say the number of the day

in the calendar, followed by the month and year.

Converting days,

weeks, months,

and years

There are 7 days in a week

and 12 months in 1 year, so

converting these units of time

can be quite tricky. Converting

days or weeks to months is

much harder, because the

number of days and weeks

in each month varies.

To convert 42 days to weeks, we divide

by 7, to give 6 weeks. To convert back

again, from weeks to days, we just multiply

by 7. This takes us back to 42.

To convert 48 months to years, we

divide by 12, which gives 4 years.

To convert back the other way, we just

multiply by 12. This takes us back to

48 months.

42 days 6 weeks 48 months 4 years

Wee

ks to days

Yea

rs^ to^ months

× 7 × 12

(^) ÷ 7
(^) ÷ 12
Days (^) to weeks
Months to years
February will
begin on a
Monday
This January begins on a
Friday and ends on a Sunday
194-195_Dates.indd 195 29/02/2016 18:04