## Topic outline

• ### Time - Addition And Subtraction

• Step1: Write the units on the top.

Step2: Write the numbers in proper place below the units. Write zero in empty place.

Step 3: Now add or subtract as per the instruction given in question.

Example 1: Add 3 hrs 35 min 50 sec and 2 hrs 40 min 34 sec 5 hrs 75 min 84 sec = 5 hrs (60 + 15) min (60 + 24) sec

= (5 + 1) hrs (15 + 1) min 24 sec

= 6hrs 16min 24sec

Explanation

Step 1: As 60 sec = 1 min, so, 60 sec i.e. 1 min is carried to minutes column and 24 sec are left in seconds column. Now, we have 75 + 1 = 76 min.

Step 2: As 60 min = 1 hr. so, 60 min i.e. 1 hr is carried over to hour column and 76 – 60 = 16 are left in min column. Now, we have 5 + 1 = 6 hr.

Example 2: Subtract 3hrs 45 min 30 sec from 8 hrs 35 min 20 sec Explanation

Step 1: As in seconds column 20 is smaller than 30, we cannot subtract 30 from 20. So, 1 min is borrowed from the minute column and we are left with 34 minutes in minute column.

Now, 1 min = 60 sec, this means 60 sec + 20 sec = 80 sec

We have 80 sec and we can subtract 30 sec from 80 sec.

80 sec – 30 sec = 50 sec

Step 2: As in minutes column 34 is smaller than 45, we cannot subtract 45 from 34. So, 1 hr is borrowed from the hours column and we are left with 7 hrs in hours column.

Now, 1 hour = 60 min, this means 60 min + 34 min = 94 min

We have 94 min and we can subtract 45 min from 94 min.

94 min – 45 min = 49 min

Step 3: Now subtract 3 hrs from 7 hrs i.e. 7 – 3 = 4hrs

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