Page 165 - Math Genius C3

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Example 2: Subtract 28 m 62 cm from 75 m 91 cm.

Solution: Write the given lengths in the correct columns such that the smaller length
is written below the bigger length. Then subtract by following the steps:

Step 1: Subtract ‘cm’. m cm

91 cm – 62 cm = 29 cm 6 15 8 11
7 5 9 1
Write 29 in the cm column.
– 2 8 6 2
Step 2: Subtract ‘m’. 75 m – 28 m = 47 m 4 7 2 9

Write 47 in the m column.

Thus, 75 m 91 cm – 28 m 62 cm = 47 m 29 cm.

Example 3: Subtract 18 km 525 m from 25 km 118 m.

Solution: Write the given lengths in the correct columns such that the smaller length is
written below the bigger length. Then subtract them by following the steps:

Step 1: Subtract ‘m’. Since 118 < 525, we cannot subtract 525 m from 118 m.

So, we regroup km and m.

25 km 118 m = 24 km 1118 m km m

Now, 1118 m – 525 m = 593 m 14 10
1 4 0 11
Write 593 under the m column. 2 5 1 1 8

Step 2: Subtract ‘km’. 24 km – 18 km = 6 km – 1 8 5 2 5
6 5 9 3
Write 6 under the km column.

Thus, 25 km 118 m – 18 km 525 m = 6 km 593 m

Example 4: Subtract 4 km 780 m from 15 km 222 m.

Solution: We can also first convert kilometre and metres into metres, and then subtract.

15 km 222 m = 15222 m 11

4 km 780 m = 4780 m 4 1 12

Now, we subtract 4780 m from 15222 m 1 5 2 2 2 m
– 4 7 8 0 m
15222 m – 4780 m = 10442 m 1 0 4 4 2 m

= 10 km 442 m

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