Q1.
Fill in the blanks with numbers, and boxes by signs, so that the expressions on both sides are equal. (a) 3 × (6 + 7) = 3 × 6 + 3 × 7 (b) (8 + 3) × 4 = 8 × 4 + 3 × 4 (c) 3 × (5 + 8) = 3 × 5 ☐ 3 × ____ (d) (9 + 2) × 4 = 9 × 4 ☐ 2 × ____ (e) 3 × (____ + 4) = 3 ____ + ____ (f) (____ + 6) × 4 = 13 × 4 + ____ (g) 3 × (____ + ____) = 3 × 5 + 3 × 2 (h) (____ + ____) × ____ = 2 × 4 + 3 × 4 (i) 5 × (9 – 2) = 5 × 9 – 5 × ____ (j) (5 – 2) × 7 = 5 × 7 – 2 × ____ (k) 5 × (8 – 3) = 5 × 8 ☐ 5 × ____ (l) (8 – 3) × 7 = 8 × 7 ☐ 3 × 7 (m) 5 × (12 – ____) = ____ ☐ 5 × ____ (n) (15 – ____) × 7 = ____ ☐ 6 × 7 (o) 5 × (____ – ____) = 5 × 9 – 5 × 4 (p) (____ – ____) × ____ = 17 × 7 – 9 × 7
Answer
Multiply the outside number into every term inside the bracket, keeping each sign.
(a) 3 × (6 + 7) = 3 × 6 + 3 × 7 (given)
(b) (8 + 3) × 4 = 8 × 4 + 3 × 4 (given)
(c) 3 × (5 + 8) = 3 × 5 + 3 × 8
(d) (9 + 2) × 4 = 9 × 4 + 2 × 4
(e) 3 × (10 + 4) = 3 × 10 + 3 × 4
(f) (13 + 6) × 4 = 13 × 4 + 6 × 4
(g) 3 × (5 + 2) = 3 × 5 + 3 × 2
(h) (2 + 3) × 4 = 2 × 4 + 3 × 4
(i) 5 × (9 – 2) = 5 × 9 – 5 × 2
(j) (5 – 2) × 7 = 5 × 7 – 2 × 7
(k) 5 × (8 – 3) = 5 × 8 – 5 × 3
(l) (8 – 3) × 7 = 8 × 7 – 3 × 7
(m) 5 × (12 – 3) = 5 × 12 – 5 × 3
(n) (15 – 6) × 7 = 15 × 7 – 6 × 7
(o) 5 × (9 – 4) = 5 × 9 – 5 × 4
(p) (17 – 9) × 7 = 17 × 7 – 9 × 7
(b) (8 + 3) × 4 = 8 × 4 + 3 × 4 (given)
(c) 3 × (5 + 8) = 3 × 5 + 3 × 8
(d) (9 + 2) × 4 = 9 × 4 + 2 × 4
(e) 3 × (10 + 4) = 3 × 10 + 3 × 4
(f) (13 + 6) × 4 = 13 × 4 + 6 × 4
(g) 3 × (5 + 2) = 3 × 5 + 3 × 2
(h) (2 + 3) × 4 = 2 × 4 + 3 × 4
(i) 5 × (9 – 2) = 5 × 9 – 5 × 2
(j) (5 – 2) × 7 = 5 × 7 – 2 × 7
(k) 5 × (8 – 3) = 5 × 8 – 5 × 3
(l) (8 – 3) × 7 = 8 × 7 – 3 × 7
(m) 5 × (12 – 3) = 5 × 12 – 5 × 3
(n) (15 – 6) × 7 = 15 × 7 – 6 × 7
(o) 5 × (9 – 4) = 5 × 9 – 5 × 4
(p) (17 – 9) × 7 = 17 × 7 – 9 × 7
Why it happens: The distributive property says a × (b + c) = a × b + a × c and a × (b – c) = a × b – a × c. In (e) and (m) any number may be used in the first blank, as long as the same number is repeated on the right — for example 3 × (7 + 4) = 3 × 7 + 3 × 4 also works.
Check it yourself: (m) 5 × 9 = 45 and 60 – 15 = 45 ✓ ; (n) 9 × 7 = 63 and 105 – 42 = 63 ✓