Question

Estimate the following by rounding off to the nearest metre or km:
1. 12 m 86 cm +23 m 73 cm
2. 26 km 342 m + 72 km 399 m
3. 286 m 89 cm + 371 m 24 cm
4. 73 km 351 m - 28 km 942 m
5. 941 m 26 cm - 639 m 44 cm
6. 43 km 962 m +84 km 632 m
7. 32 m 44 cm + 44 m 49 cm
8. 333 km 994 m + 136 km 346 m
9. 92 m 45 cm - 42 m 84 cm
10. 731 km 364 m - 212 km 472 m​

Answer 1

Answer:

I think it will help you

Answer 2

The answers are as follows;

1. 37 meters
2. 98 Km
3. 658 meters
4. 44 km
5. 302 meters
6. 128 km
7. 76 m
8. 470 km
9. 49 m
10. 519 km

GIVEN

1. 12 m 86 cm +23 m 73 cm

2. 26 km 342 m + 72 km 399 m

3. 286 m 89 cm + 371 m 24 cm

4. 73 km 351 m - 28 km 942 m

5. 941 m 26 cm - 639 m 44 cm

6. 43 km 962 m +84 km 632 m

7. 32 m 44 cm + 44 m 49 cm

8. 333 km 994 m + 136 km 346 m

9. 92 m 45 cm - 42 m 84 cm

10. 731 km 364 m - 212 km 472 m

TO FIND

To estimate the following distances

SOLUTION

We can simply solve the above problem as follows;

CONCEPT USED:

Estimation is a process of rounding of numbers in order to avoid complicated calculations.

Rounding off decimal numbers is done as follows;

1. If the digit on right side of the decimal is less than 5, The number on the left side remains as it is and digits on right side of the decimals are changed to zero.
2. If the digit on right side of the decimal is equal to or more than 5, the digit on the left side is increased by 1.

(1) 12 m 86 cm +23 m 73 cm

It can also be written as, 12.86 m + 23.73 m

Rounding off = 12.86≈ 13 , 23.75 ≈ 24

13 + 24 = 37 meters

(2) 26 km 342 m + 72 km 399 m

It can also be written as, 26.342 km + 72.399 km

Rounding off, 26.342 ≈ 26 km , 72.399 = 72 km

26 + 72 = 98Km

(3) 286 m 89 cm + 371 m 24 cm

It can also be written as; 286.89m + 371.24m

Rounding off; 286.89 ≈ 287 m , 371.24 ≈ 371 m

287 + 371 = 658 meters

(4) 73 km 351 m - 28 km 942 m

It can also be written as; 73.351 km - 28.942 km

Rounding off; 73.351 ≈ 73 km , 28.942 ≈ 29 km

73 - 29 = 44 km

(5) 941 m 26 cm - 639 m 44 cm

It can also be written as; 941.26m - 639.44 m

Rounding off, 941.26 ≈ 941 m , 639.44 ≈ 639 m

941 - 639 = 302 meters

(6) 43 km 962 m +84 km 632 m

It can also be written as; 43.962 km + 84.632 km .

Rounding off; 43.962 ≈ 44 km , 84.632 ≈ 84 km

44 + 84 = 128 km

(7) 32 m 44 cm + 44 m 49 cm

It can also be written as; 32.44 m + 44.49 m

Rounding off; 32.44 ≈ 32 m , 44.49 ≈ 44 m

32 + 44 = 76 m

(8) 333 km 994 m + 136 km 346 m

We can also write it as; 333.994 km + 136.346 km

Rounding off; 333.994 ≈ 334 km , 136.346 ≈ 136 km

334 + 136 = 470 km

(9) 92 m 45 cm - 42 m 84 cm

We can also write it as; 92.45 m - 42.84 m

Rounding off; 92.45 ≈ 92 m , 42.84 ≈ 43 m

92-43 = 49 m

(10) 731 km 364 m - 212 km 472 m

We can also write it as; 731.364 km - 212.472km

Rounding off; 731.364 ≈ 731 Km , 212.472 ≈ 212 km

731 - 212 = 519 km

Hence, The answers are as follows;

1. 37 meters
2. 98 Km
3. 658 meters
4. 44 km
5. 302 meters
6. 128 km
7. 76 m
8. 470 km
9. 49 m
10. 519 km

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