Page 161 - ICSE Math 4

Converting Hours to Minutes and Vice Versa

1
We know that 1 hour = 60 minutes or 1 h = 60 min, so we can write 1 min = h. Let’s learn
how to convert hours to minutes and vice versa. 60
Conversion of Hours to Minutes

 To convert hours to minutes, we mul ply the hours by 60.

 To convert hours and minutes to minutes, we mul ply the hours by 60 and then add
the minutes to it.

Example 3: Convert 9 hours 12 minutes to minutes.
Solu on: 9 h 12 min = (9 × 60) min + 12 min = 540 min + 12 min = 552 min

Conversion of Minutes to Hours

 To convert minutes to hours, we divide the number of minutes by 60.
 To convert minutes to hours and minutes, we divide the minutes by 60. Write the
quo ent obtained as number of hours and the remainder obtained as minutes.

Example 4: Convert 932 minutes to hours and minutes. 15  hours
1 60 932
Solu on: We know that 1 min = h
60 –60
932
Thus, 932 min = h 332
60 –300
So, 932 min = 15 h 32 min. 32  minutes

Converting Minutes to Seconds and Vice Versa

1
We know that 1 minute = 60 seconds or 1 min = 60 s, so we can write 1 s = min. Let’s
60
learn how to convert minutes to seconds and vice versa.
Conversion of Minutes to Seconds

 To convert minutes to seconds, we mul ply the number of minutes by 60.

 To convert minutes and seconds to seconds, we mul ply the minutes by 60 and then
add the seconds to it.

Example 5: Convert the following to seconds: (a) 15 min and (b) 12 min 40 s
Solu on: (a) 15 min = 15 × 60 s = 900 s Mental Maths

(b) 12 min 40 s = (12 × 60) s + 40 s
Convert the following to minutes.
= 720 s + 40 s = 760 s (a) 120 s (b) 2 h (c) 1 h 5 min
Conversion of Seconds to Minutes

 To convert seconds to minutes, we divide the seconds by 60.

 To convert seconds to minutes and seconds, we divide the seconds by 60. Write the
quo ent obtained as minutes and the remainder obtained as seconds.

151