7th Maths : Term 3 Unit 1 : Number System : Rounding of Decimals : Exercise 1.1 : Text Book Back Exercises Questions with Answers, Solution

**Exercise
1.1**

** **

**1.
Round each of the following decimals to the nearest whole number.**

**(i)
8.71 **

Underlining the digit to be rounded __8.__71. Since the digit
next to the underlined digit, 7 which is greater than 5, adding 1 to the
underlined digit. Hence the nearest whole number 8.71 rounds to is __ 9__.

**(ii)
26.01 **

Underlining the digit to be rounded 2__6__.01. Since the
digit next to the underlined digit, 0 which is less than 5, the underlined
digit 6 remains the same.

∴ The nearest whole number 26.01 rounds to is **26**.

**(iii)
69.48**

Underlining the digit to be rounded 6__9__.48. Since the
digit next to the underlined digit, 4 which is less than 5, the underlined
digit 9 remains the same.

∴ The whole number is 69.48 rounds to is **69**.

**(iv)
103.72**

Underlining the digit to be rounded 10__3__.72 since the
digit next to the underlined digit, 7 which is greater than 5, we add 1 to the
under lined digit.

Hence the nearest whole number 103.72 rounds to is **104**.

** (v) 49.84 **

Underlining the digit to be rounded 4__9__.84. Since the
digit next to the underlined digit 8 which is greater than 5, we add 1 to the
underlined digit.

Hence the nearest whole number 49.84 rounds to **50**.

**(vi)
101.35**

Underlining the digit to be rounded 10__1__.35. Since the
digit next to the underlined digit 3 is less than 5, the underlined digit 1
remains the same.

Hence the nearest whole number 101.35 rounds to is **101**.

**(vii)
39.814 **

Underlining the digit to be rounded 3__9__.814. Since the
digit next to the underlined digit 8 is greater than 5, we add 1 to the
underlined digit.

Hence the nearest whole number 39.814 rounds to is **40**.

**(viii)
1.23 **

Underlining the digit to be rounded __1__.23. Since the digit
next to the underlined digit 2, is less than 5, the underlined digit 1 remains
the same.

Hence the nearest whole number 1.23 rounds to is **1**.

** **

**2.
Round each decimal number to the given place value.**

**(i)
5.992 to tenth place**

Underlining the digit to be rounded 5.__9__92. Since the
digit next to the underlined digit is 9 greater than 5, we add 1 to the
underlined digit. Hence the rounded number is ** 6.0**.

**(ii)
21.805 to hundredth place**

Underlining the digit to be rounded 21.8__0__5 since the
digit next to the underlined digit is 5, we add I to the underlined digit.
Hence the rounded number is **21.81**.

**(iii)
35.0014 to thousandth place**

Underlining the digit to be rounded 35.00__1__4. Since the
digit next to the underlined digit is 4 less than 5 the underlined digit
remains the same. Hence the rounded number is **35.001**.

** **

**3.
Round the following decimal numbers upto 1 places of decimal**

**(i)
123.37 **

Rounding 123.37 upto one places of decimal means round to the nearest
tenths place. Underling the digit in the tenths place of 123.37 gives 123.__3__7.
Since the digit next to the tenth place value is 7 which is greater than 5, we
add 1 to the underlined digit to get 123.4. Hence the rounded value of 123.37
upto one places of decimal is **123.4**.

**(ii)
19.99 **

Rounding 19.99 upto one places of decimal means round to the
nearest tenth place. Underling the digit in the tenths place of 19.99 gives 19.__9__9.
Since the digit next to the tenth place value is 9 which is greater than 5, we add
1 to the underlined digit to get 20. Hence the rounded value of 19.99 upto one
places of decimal is **20.0**.

**(iii)
910.546**

Rounding 910.546 upto one places of decimal means round to the
nearest tenths place underlining the digit in the tenths place of 910.546 gives
910.__5__46. Since the digit next to the tenth place value is 4, which is
less than 5 the underlined digit remains the same. Hence the rounded value of
910.546 upto one places of decimal is **910.5**.

** **

**4.
Round the following decimal numbers upto 2 places of decimal**

**(i)
87.755**

Rounding 87.755 upto 2 places of decimal means round to the
nearest hundredths place. Underlining the digit in the hundredth place of
87.755 gives 87.7__5__5. Since the digit next to the hundredth place value
is 5, we add 1 to the underlined digit.

Hence the rounded value of 87.755 upto two places of decimal is
**87.76**.

**(ii)
301.513**

Rounding 301.51 upto 2 places of decimal means round to the
nearest hundredths place. Underlining the digit in the hundredth place of
301.513 gives 301.5__1__3. Since the digit next to the underlined digit 3 is
less than 5, the underlined digit remains the same.

∴ The rounded value of 301.513 upto 2 places of decimal is
**301.51**.

** (iii) 79.997**

Rounding 79.997 upto 2 places of decimal means round to the
nearest hundredths place. Underlining the digit in the hundredth place of
79.997 gives 79.9__9__7. Since the digit next to the underlined digit 7 is
greater than 5, we add 1 to the underlined number.

Hence the rounded value of 79.997 upto 2 places of decimal is
**80.00**.

** **

**5.
Round the following decimal numbers upto 3 place of decimal**

**(i)
24.4003 **

Rounding 24.4003 upto 3 places of decimal means rounding to the
nearest thousandths place. Underlining the digit in the thousandths place of
24.4003 gives 24.40__0__3. In 24.40__0__3 the digit next to the
thousandths value is 3 which is less than 5.

∴ The underlined digit remains the same. So the rounded value of
24.4003 upto 3 places of decimal is **24.400**.

**(ii)
1251.2345 **

Rounding 1251.2345 upto 3 places of decimal means rounding to
the nearest thousandths place. Underlining the digit in the thousandths place
of 1251.2345 gives 1251.23__4__5, the digit next to the thousandths place
value is 5 and so we add 1 to the underlined digit. So the rounded value of
1251.2345 upto 3 places of decimal is **1251.235**.

**(iii)
61.00203**

Rounding 61.00203 upto 3 places of decimal means rounding to the
nearest thousandths place. Underlining the digit in the thousandth place of
61.00__2__03 gives 61.00__2__03. In 61.00__2__03, the digit next to
the thousandths place value is 0, which is less than 5.

Hence the underlined digit remains the same. So the rounded
value of 61.00203 upto 3 places of decimal is **61.002**.

__ANSWERS:__

**Exercise 1.1**

1. (i) 9 (ii) 26 (iii)
69 (iv) 104 (v) 50 (vi) 101 (vii) 40 (viii) 1

2. (i) 6.0 (ii) 21.81
(iii) 35.001

3. (i) 123.4 (ii) 20.0
(iii) 910.6

4. (i) 87.76 (ii)
301.51 (iii) 80.00

5. (i) 24.400 (ii) 1251.235 (iii) 61.002

Tags : Questions with Answers, Solution | Number System | Term 3 Chapter 1 | 7th Maths , 7th Maths : Term 3 Unit 1 : Number System

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7th Maths : Term 3 Unit 1 : Number System : Exercise 1.1 (Rounding of Decimals) | Questions with Answers, Solution | Number System | Term 3 Chapter 1 | 7th Maths

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