NCERT Class 7 Mathematics

INTEGERS 19 TRY THESE Or, we can do it this way, (–25) × 37 × 4 = (–25) × 4 × 37 = [(–25) × 4] × 37 = (–100) × 37 = –3700 Which ...

20 MATHEMATICS [(–30) × 13] + [(–30) × (–3)] = –390 + 90 = –300 So, (–30) × [13 + (–3)] = [(–30) × 13] + [(–30) × (–3)] EXAMPLE ...

INTEGERS 21 EXERCISE 1.3 Find each of the following products: (a) 3 × (–1) (b) (–1) × 225 (c) (–21) × (–30) (d) (–316) × (–1) ...

22 MATHEMATICS (b) What is the number of white cement bags it must sell to have neither profit nor loss, if the number of grey b ...

INTEGERS 23  We also observe that: 72 ÷ (–8) = –9 and 50 ÷ (–10) = –5 72 ÷ (–9) = – 8 50 ÷ (–5) = –10 So we can say that when w ...

24 MATHEMATICS You can see from the table that (– 8) ÷ (– 4) ≠ (– 4) ÷ (– 8). Is (– 9) ÷ 3 the same as 3 ÷ (– 9)? Is (– 30) ÷ (– ...

INTEGERS 25 answered all the questions and scored (–12) marks though he got 4 correct answers. How many incorrect answers had th ...

26 MATHEMATICS i.e., Profit earned = – Loss incurred. Now, profit earned by selling 70 pens = Rs 70 Hence, loss incurred by sell ...

INTEGERS 27 WHAT HAVE WE DISCUSSED? Integers are a bigger collection of numbers which is formed by whole numbers and their nega ...

28 MATHEMATICS The properties of commutativity, associativity under addition and multiplication, and the distributive property ...

FRACTIONS AND DECIMALS 29 2.1 INTRODUCTION You have learnt fractions and decimals in earlier classes. The study of fractions inc ...

30 MATHEMATICS EXAMPLE 2 Ramesh solved 2 7 part of an exercise while Seema solved 4 5 of it. Who solved lesser part? SOLUTION In ...

FRACTIONS AND DECIMALS 31 Thus, time devoted by her for other subjects = 17 14 35  h = 17 5 14 3–h 15 15   = 85 – 42 ...

32 MATHEMATICS Ritu ate 3 5 part of an apple and the remaining apple was eaten by her brother Somu. How much part of the apple ...

FRACTIONS AND DECIMALS 33 The shaded portions in Fig 2.1 taken together are the same as the shaded portion in Fig 2.2, i.e., we ...

34 MATHEMATICS For improper fractions also we have, 2 5 3  =^25 3  = 10 3 Try, 3 8 7  =? 4 7 5  =? Thus, to multiply a whole ...

FRACTIONS AND DECIMALS 35 Also, look at these similar squares (Fig 2.7). Each shaded portion represents 1 2 of 1. So, both the s ...

36 MATHEMATICS Thus, the number of students who like to study English = 1 5 of 40 = (^140) 5  = 8. (ii) Try yourself. (iii) The ...

FRACTIONS AND DECIMALS 37 Shade: (i) 1 2 of the circles in box (a) (ii) 2 3 of the triangles in box (b) (iii) 3 5 of the squar ...

38 MATHEMATICS folding the part once. What will one of the pieces represent? It will represent 1 2 of 9 4 or 1 2 × 9 4 . Let us ...