Ncert solutions

Ncert solutions

Grade 7

Algebraic Expressions | Exercise 12.4

Question 1

Q1) Observe the patterns of digits made from line segments of equal length. You will find such segmented digits on the display of electronic watches or calculators.

If the number of digits formed is taken to be n, the number of segments required to form n digits is given by the algebraic expression appearing on the right of each pattern. How many segments are required to form 5, 10, 100 digits of the kind 6, 4, 3.

Solution:

i) For 5 figures, the number of line segments

= 5 x 5 +1

= 25 + 1

= 26

For 10 figures, the number of line segments

= 5 x 10 + 1

= 50 + 1

= 51

For 100 figures, the number of line segments

= 5 x 100 +1

= 500 + 1

= 501

ii) For 5 figures, the number of line segments

= 3 x 5 +1

= 15 + 1

= 16

For 10 figures, the number of line segments

= 3 x 10 + 1

= 30 + 1

= 31

For 100 figures, the number of line segments

= 3 x 100 +1

= 300 + 1

= 301

iii) For 5 figures, the number of line segments

= 5 x 5 +2

= 25 + 2

= 27

For 10 figures, the number of line segments

= 5 x 10 + 2

= 50 + 2

= 52

For 100 figures, the number of line segments

= 5 x 100 +2

= 500 + 2

= 502

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Question 1

Q1) Observe the patterns of digits made from line segments of equal length. You will find such segmented digits on the display of electronic watches or calculators.

If the number of digits formed is taken to be n, the number of segments required to form n digits is given by the algebraic expression appearing on the right of each pattern. How many segments are required to form 5, 10, 100 digits of the kind 6, 4, 3.

Solution:

i) For 5 figures, the number of line segments

= 5 x 5 +1

= 25 + 1

= 26

For 10 figures, the number of line segments

= 5 x 10 + 1

= 50 + 1

= 51

For 100 figures, the number of line segments

= 5 x 100 +1

= 500 + 1

= 501

ii) For 5 figures, the number of line segments

= 3 x 5 +1

= 15 + 1

= 16

For 10 figures, the number of line segments

= 3 x 10 + 1

= 30 + 1

= 31

For 100 figures, the number of line segments

= 3 x 100 +1

= 300 + 1

= 301

iii) For 5 figures, the number of line segments

= 5 x 5 +2

= 25 + 2

= 27

For 10 figures, the number of line segments

= 5 x 10 + 2

= 50 + 2

= 52

For 100 figures, the number of line segments

= 5 x 100 +2

= 500 + 2

= 502

Still have questions? Our expert teachers can help you out

Book a free class now

Want to top your mathematics exam ?

Learn from an expert tutor.

Book a free class now
subject-cta
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