In making geometrical shapes we need to use some tools. We shall begin with listing these tools, describing them and looking at how they are used. Name, Figure and Use Description 1. The Ruler To draw and measure line segments The ruler is graduated into their lengths, centimetres along one edge and inches along the […]

## 7.2 Perpendiculars

You know that two lines (or rays or segments) are said to be a perpendicular if they intersect so as to angles formed between them are right angles. The corners of your textbook indicate lines meeting at the right angles. Do YourselfTake a piece of paper. Fold it along the middle and make the crease. […]

## The 21st Century and Information and Communication Technology

The concept of wealth that prevailed in the last century has radically changed. The whole world rightly acknowledges that the wealth of the 21st century is knowledge. It means that neither agriculture, mineral resources and energy, nor industry and business are the sources of wealth. Human beings are because they are capable of searching knowledge. […]

## Exercise 1.6

1. How many prime numbers are there from 28 to 40 ? (a) 3 (b) 4 (c) 5 (d) 6 2. Which one of the following are co-prime pairs ? (a) 12, 18 (b) 19, 38 (c) 22, 27 (d) 28, 35 3. What is the H.C.F. of 12, […]

## 1.24 H.C.F. and L.C.M. of decimal fractions

Determination of H.C.F. and L.C.M. of 2, 1.2 and 0.08 Given fractions are exactly equal to 2.00, 1.20 and 0.08 Now, H.C.F. of 200, 120 and 8 is = 8 and L.C.M. = 600 \(\therefore\) The required H.C.F. = 0.08 and the L.C.M. = 600 Observe : In some cases, necessary zeroes are put in […]

## 1.23 Division of decimal fractions

Example 4. Divide 808.9 by 25. Solution : Alternative method : Solution : \(808.9 \div 25\) = \(\frac{808.9}{25} = \frac{808.9 \times 4}{25 \times 4}\) = \frac{3235.6}{100} = \(32.356\) Required quotient is \(32.356\). Observe : ➢ Division has been carried on as in the case of division of integers. ➢ The decimal point has been inserted […]