Exercise : 1


Directions (Qs. 1 - 10): What will come in place of the question mark (?) in the following questions?

1. 49 × 49 × 49 × 49 = 7?
(a) 4
(b) 7
(c) 8
(d) 16
(e) None of these
Ans.c

49 × 49 × 49 × 49 = 7?

or, 72 × 72 × 72 × 72 = 7?

or 78 = 7? or, ? = 8

2. (500 + 200) × 4 × (3 + 2) = ?
(a) 2902
(b) 14000
(c) 8402
(d) 16800
(e) None of these
Ans.b

(500 + 200) × 4 × (3 + 2) = ?

or, ? = 700 × 4 × 5 = 14000

3. 16.02 × 0.001 = ?
(a) 0.1602
(b) 0.001602
(c) 1.6021
(d) 0.01602
(e) None of these
Ans.d

16.02 × 0.001 = ?

or,? = 0.01602

4. ?50 = 60.5?
(a) 55
(b) 1512.5
(c) 52.5
(d) 57.5
(e) None of these
Ans.a

?50 = 60.5?

or,?2 = 50 × 60.5 or, ?2 = 3025

or, ? = \(\sqrt{3025}\) = 55

5. 5400 ÷ 9 ÷ 3 = ?
(a) 1800
(b) 900
(c) 450
(d) 300
(e) None of these
Ans.e

5400 ÷ 9 ÷ 3 = ?

or, ? = 5400 × \(\frac{1}{9 \times 3} = 200\)

6. 15 + 17 + 23 = ?
(a) 11105
(b) 104105
(c) 117
(d) 12105
(e) None of these
Ans.a

15 + 17 + 23 = ?

or, ? = \(\frac{21 + 15 + 70}{105} = \frac{106}{105} = 1\tfrac{1}{105}\)

7. 10150 ÷ 10146 = ?
(a) 106
(b) 100000
(c) 1000
(d) 10000
(e) None of these
Ans.d

10150 ÷ 10146 = ?

or ? = \(\frac{10^{150}}{10^{146}} = 10^{150 - 146}\)

i.e, \(\left [ \frac{m^{x}}{m^{y}} = m^{x - y} \right ]\)

= 104 = 10000

8. 200 + 5 × 4 = ?
(a) 820
(b) 202
(c) 420
(d) 209
(e) None of these
Ans.e

200 + 5 × 4 = ?

or, ? = 200 + 20 = 220

9. ?% of 360 = 129.6
(a) 277
(b) 36
(c) 64
(d) 72
(e) None of these
Ans.b

?% of 360 = 129.6

or, ? = \(\frac{129.6 \times 100}{360} = 36\)

10. \(\left(\sqrt{49} \right)^{2}\)
(a) 7
(b) 14
(c) 49
(d) 21
(e) None of these
Ans.c

\(\left(\sqrt{49} \right)^{2}\) = ?

or, ? = 49