Estimate the following products using general rule:
,b>(a) $578 \times 161$
(b) $5281 \times 3491$
(c) $1291 \times 592$
(d) $9250 \times 29$
Make four more such examples.

Given:

(a) $578 \times 161$

(b) $5281 \times 3491$

(c) $1291 \times 592$

(d) $9250 \times 29$

To do:

We have to estimate the given products using general rule.

Solution:

According to the general rule,

Round off each factor to its greatest place, then multiply the rounded off factors.

(a) Rounding off 578, we get 600

Rounding off 161, we get 200

Therefore,

Estimate of $578 \times 161$ using general rule is,

$600\times200=120000$

(b) Rounding off 5281, we get 5000

Rounding off 3491, we get 3500

Therefore,

Estimate of \( 5281 \times 3491 \) using general rule is,

$5000\times3500=17500000$.

(c) Rounding off 1291, we get 1300

Rounding off 592, we get 600

Therefore,

Estimate of \( 1291 \times 592 \) using general rule is,

$1300\times600=780000$.

(d) Rounding off 9250, we get 9000

Rounding off 29, we get 30

Therefore,

Estimate of \( 9250 \times 29 \) using general rule is,

$9000\times30=270000$.

Four more examples are as follows:

$113\times21=100\times20$

$=2000$

$53\times4050=50\times4000$

$=200000$

$304\times49=300\times50$

$=15000$

$989\times99=1000\times100$

$=100000$

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Updated on: 10-Oct-2022

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