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NCERT Solutions for Class 4th Maths Chapter 12 AM and PM — In-text Questions

Book page 179 – 180 Updated on2026-09-19

Q1.
Read the following table and see how we read and write time using AM/PM and the digital clock. Discuss what you notice about the two different ways.
Time in AM/PMTime in the digital clock
12:00 AM00:00 hours
1:00 AM1:00 hours
3:00 AM3:00 hours
7:15 AM7:15 hours
9:45 AM_______
_______11:20 hours
12:00 PM12:00 hours
1:00 PM13:00 hours
3:00 PM_______
5:20 PM_______
_______20:00 hours
11:45 PM23:45 hours
The table printed on page 180.
Answer
Time in AM/PMTime in the digital clock
12:00 AM00:00 hours
1:00 AM1:00 hours
3:00 AM3:00 hours
7:15 AM7:15 hours
9:45 AM_______
_______11:20 hours
12:00 PM12:00 hours
1:00 PM13:00 hours
3:00 PM_______
5:20 PM_______
_______20:00 hours
11:45 PM23:45 hours
The table printed on page 180.

Here is what the table shows.

  • The AM/PM way uses only the numbers 1 to 12, and then adds AM or PM to say which half of the day it is.
  • The digital clock way uses the numbers 0 to 23, so it needs no AM and no PM.
  • For every morning time the two numbers are the same — 3:00 AM is 3:00 hours, 7:15 AM is 7:15 hours.
  • Midnight is the one morning time that changes: 12:00 AM becomes 00:00 hours.
  • After 12 noon you add 12 to the hour: 1:00 PM becomes 13:00 hours, 11:45 PM becomes 23:45 hours.
  • The minutes never change. Only the hour number changes.
Why it happens: A day has 24 hours but a clock face has only 12 numbers. AM and PM tell us which round of the 12 we are in; the digital clock counts straight on from 0 to 23 instead.
Tip: AM means the time from midnight to noon, and PM means the time from noon to midnight. 8:00 AM is breakfast time; 8:00 PM is dinner time.
Q2.
Fill in the blanks by writing time in the appropriate format.
Time in AM/PMTime in the digital clock
12:00 AM00:00 hours
1:00 AM1:00 hours
3:00 AM3:00 hours
7:15 AM7:15 hours
9:45 AM_______
_______11:20 hours
12:00 PM12:00 hours
1:00 PM13:00 hours
3:00 PM_______
5:20 PM_______
_______20:00 hours
11:45 PM23:45 hours
The table printed on page 180.
Answer
Time in AM/PMTime in the digital clock
12:00 AM00:00 hours
1:00 AM1:00 hours
3:00 AM3:00 hours
7:15 AM7:15 hours
9:45 AM_______
_______11:20 hours
12:00 PM12:00 hours
1:00 PM13:00 hours
3:00 PM_______
5:20 PM_______
_______20:00 hours
11:45 PM23:45 hours
The table printed on page 180.

Use the rule from the table: before noon the numbers match, after noon add 12 to the hour.

9:45 AM → morning, so it stays the same → 9:45 hours
11:20 hours → less than 12, so it is morning → 11:20 AM
3:00 PM → 3 + 12 = 15 → 15:00 hours
5:20 PM → 5 + 12 = 17 → 17:20 hours
20:00 hours → 20 − 12 = 8, and it is past noon → 8:00 PM
Time in AM/PMTime in the digital clock
12:00 AM00:00 hours
1:00 AM1:00 hours
3:00 AM3:00 hours
7:15 AM7:15 hours
9:45 AM9:45 hours
11:20 AM11:20 hours
12:00 PM12:00 hours
1:00 PM13:00 hours
3:00 PM15:00 hours
5:20 PM17:20 hours
8:00 PM20:00 hours
11:45 PM23:45 hours
The same table with every blank filled in.
Why it happens: Adding 12 moves the time from the first round of the clock to the second round of the same day.
Check it yourself: 5:20 PM is tea time in the evening. On the digital clock it reads 17:20 hours, and 17 − 12 = 5, which brings you right back.
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