EXERCISE-1E
Question 1
Estimate each of the following products by rounding off each number to the nearest ten.
Q.1. $38 \times 63$.
Ans. $(38 \times 63)$
38 estimated to the nearest ten $=40$
63 estimated to the nearest ten $=60$
$\therefore 40 \times 60=2400$
Question 2
Ans. $(54 \times 47)$
54 estimated to the nearest ten $=50$
47 estimated to the nearest ten $=50$
$\therefore 50 \times 50=2500$
Question 3
Q.3. $28 \times 63$.
Ans. $(28 \times 63)$
28 estimated to the nearest ten $=30$
63 estimated to the nearest ten $=60$
$\therefore 30 \times 60=1800$
Question 4
Q.4. $42 \times 75$.
Ans. $(42 \times 75)$
42 estimated to the nearest ten $=40$
75 estimated to the nearest ten $=80$
$\therefore 40 \times 80=3200$
Question 5
Ans. $(64 \times 58)$
64 estimated to the nearest ten $=60$
58 estimated to the nearest ten $=60$
$\therefore 60 \times 60=3600$
Question 6
Ans. $(15 \times 34)$
15 estimated to the nearest ten $=20$
34 estimated to the nearest ten $=30$
$\therefore 20 \times 30=600$
Question 7
Q.7. $376 \times 123$.
Ans. $(376 \times 123)$
376 estimated to the nearest hundred $=400$
123 estimated to the nearest hundred $=100$
$\therefore 400 \times 100=40000$
Question 8
Ans. $(264 \times 147)$
264 estimated to the nearest hundred $=300$
147 estimated to the nearest hundred $=100$
$\therefore 300 \times 100=30000$
Question 9
Q.9. $423 \times 158$.
Ans. $(423 \times 158)$
423 estimated to the nearest hundred $=400$
158 estimated to the nearest hundred $=200$
$\therefore 400 \times 200=80000$
Question 10
Ans. $(509 \times 179)$
509 estimated to the nearest hundred $=500$
179 estimated to the nearest hundred $=200$
$\therefore 500 \times 200=100000$
Question 11
Ans. $(392 \times 138)$
392 estimated to the nearest hundred $=400$
138 estimated to the nearest hundred $=100$
$\therefore 400 \times 100=40000$
Question 12
Ans. $(271 \times 339)$
271 estimated to the nearest hundred $=300$
339 estimated to the nearest hundred $=300$
$\therefore 300 \times 300=90000$
Question 13
Q.13. $183 \times 154$.
Ans. $(183 \times 154)$
183 is rounded off upwards $=200$
154 is rounded off downwards $=100$
$\therefore 200 \times 100=20000$
Question 14
Ans. $(267 \times 146)$
267 is rounded off upwards $=300$
146 is rounded off downwards $=100$
$\therefore 300 \times 100=30000$
Question 15
Ans. $(359 \times 76)$
359 is rounded off upwards $=400$
76 is rounded off downwards $=70$
$\therefore 400 \times 70=28000$
Question 16
Ans. $(472 \times 158)$
472 is rounded off upwards $=500$
158 is rounded off downwards $=100$
$\therefore 500 \times 100=50000$
Question 17
Ans. $(680 \times 164)$
680 is rounded off upwards $=700$
164 is rounded off downwards $=100$
$\therefore 700 \times 100=70000$
Question 18
Ans. $(255 \times 350)$
255 is rounded off upwards $=300$
350 is rounded off downwards $=300$
$\therefore 300 \times 300=90000$
Question 19
Estimate each of the following products by rounding off the first number downwards and the second number upwards :
Q.19. $356 \times 278$.
Ans. $(356 \times 278)$
356 is rounded off downwards $=300$
278 is rounded off upwards $=300$
$\therefore 300 \times 300=90000$
Question 20
Ans. $(472 \times 76)$
472 is rounded off downwards $=400$
76 is rounded off upwards $=80$
$\therefore 400 \times 80=32000$
Question 21
Ans. $(578 \times 369)$
578 is rounded off downwards $=500$
369 is rounded off upwards $=400$
$\therefore 500 \times 400=200000$
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