Q1: Find the values of the following expressions by writing the terms in each case.
(a) 35 – 8 + 9
Ans: Terms: 35, -8, 9.
Expression: 35 + (-8) + 9 =
27 + 9 = 36.
(b) 50 – 3 × 7 + 13
Ans: Terms: 50, -3 × 7, 13.
Expression: 50 + (-21) + 13
= 50 – 21 + 13 = 42.
(c) 60 – 15 + 5 + 10
Ans: Terms: 60, -15, 5, 10.
Expression: 60 + (-15) + 5 + 10
= 45 + 5 + 10 = 60.
Q2: Use ‘>’ or ‘<’ or ‘=’ in each of the following expressions to compare them. Can you do it without complicated calculations? Explain your thinking in each case.
(a) 322 + 215 ____ 324 + 213
Ans: Left side: 322 + 215 = 537
Right side: 324 + 213 = 537
322 + 215 = 324 + 213 (They are equal)
(b) 571 + 432 ____ 570 + 434
Ans: Left side: 571 + 432 = 1003
Right side: 570 + 434 = 1004571 + 432 < 570 + 434
(c) 418 – 234 ____ 414 – 238
Ans: Left side: 418 – 234 = 184
Right side: 414 – 238 = 176
418 – 234 > 414 – 238
Q3: Compare and answer if LHS = RHS .
(a) 4 × (5 + 8) = 4 × 5 + 4 × 8
Ans: This is already correct.
4 × (5 + 8) = 4 × 13 = 52
4 × 5 + 4 × 8 = 20 + 32 = 52
(b) 6 × (3 + 7) = 6 × 3 + 6 × 7
Ans: This is already correct.
6 × (3 + 7) = 6 × 10 = 60
6 × 3 + 6 × 7 = 18 + 42 = 60
Q4: Fill in the blanks to make the expressions equal on both sides of the = sign:
(a) 15 + 6 = _____ + 8
Ans: 15 + 6 = 21,
so 13 + 8 = 21.
The blank is 13.
(b) 30 + _____ = 5 × 8
Ans: 5 × 8 = 40,
so 30 + 10 = 40.
The blank is 10.
(c) 9 × _____ = 72 ÷ 3
Ans:
72 ÷ 3 = 24,
so 9 × 4 = 24.
The blank is 4.
(d) 50 – _____ = 40
Ans: 50 – 10 = 40.
The blank is 10.
Q5: Compare the following pairs of expressions using ‘<‘, ‘>’, or ‘=’
(a) 72 × 34 – 15 ___ 72 × 30 – 15
Ans: 72 × 34 = 72 × (30 + 4) = 72 × 30 + 72 × 4.
So, 72 × 34 – 15 = 72 × 30 + 72 × 4 – 15, and 72 × 30 – 15 = 72 × 30 – 15.
So, 72 × 34 – 15 > 72 × 30 – 15
(b) 63 – 9 + 5 ___ 63 – 9 + 5
Ans: Same expression.
So, 63 – 9 + 5 = 63 – 9 + 5.